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Tseng’s Miniature Student Pharmacopeia DRUGS OF THE PERIPHERAL NERVOUS SYSTEM (AUTONOMIC + SOMATOMOTOR) MUSCARINIC AGONISTS Drug (Generic Name) Acetylcholine Class, Mechanism Receptor Activity Natural Choline Ester All M, All N Actions and Therapeutic Uses AR Absolute Precautions No therapeutic use since immediately hydrolyzed by plasma cholinesterase. Methacoline Choline Ester Derivative M>N Provocative diagnostic test for airway hyperreactivity Carbachol Choline Ester Derivative M + NN Post-operative miotic for cataract surgery (widens the angle, reducing IOP) Bethenecol Choline Ester Derivative M3 Pilocarpine Natural Alkaloid M3 Urinary retention (atonic bladder) [contracts detrussor] GI atonia and gastroparesis (postoperative) Xerostomia secondary to Sjogren’s Second-line for open-angle glaucoma (miotic) Clearance, Metabolism, other Remarks AChe and reuptake of choline Asthma, β2 blockers, peptic ulceration Has slight nicotinic affinity Has slight nicotinic affinity Not affine for hydrolysis by AChE Clearance by diffusion out of synaptic cleft Asthma Iritis Posterior adhesions NICOTINIC AGONISTS Nicotine Veranicline Exogenous Alkaloid NN and NM Smoking cessation Downregulates sympathetic and parasympathetic activity (predominant tone) Partial Nicotinic Agonist α4β2 N and 5-HT3 in CNS Smoking cessation Renal insufficiency Renal excretion without transformation ACETYLCHOLINESTERASE INHIBITORS Simple Quaternary Ammonium Alcohol Competitive Inhibitor Carbamyl Ester with Quaternary Ammonium Competitive Inhibitor (effectively irreversible) Provocative diagnostic test for myasthenia gravis Postoperative reversal of NMJ blockade Physostigmine Carbamyl Ester with Tertiary Ammonium Competitive Inhibitor (effectively irreversible) Echothiophate Organophophate Irreversible Competitive Inhibitor Edrophonium Neostigmine GI obstruction, ileus Urinary tract obstruction Asthma GI obstruction, ileus Urinary tract obstruction Asthma Stimulate muscarinic receptors at all targets DOC for reversal of muscarinic antagonist poisoning Second-line treatment of open-angle glaucoma GI obstruction, ileus Urinary tract obstruction Asthma Quaternary ammonium derivatives are not absorbed by the GI tract Second-line treatment for open-angle glaucoma (miotic) Uveitis DOC for treatment of myasthenia gravis Some stimulation of autonomic ganglia ACETYLCHOLINESTERASE SALVAGE Pralodoxime Cholinesterase Reactivator Activated Nucleophile Reveral of AChE inactivation (phosphorylation) by organophosphates Neostigmine for myasthenia gravis Renal insufficiency Must be administered within 24 h. after inhibition Transformation in liver and renal excretion MUSCARINIC ANTAGONISTS Atropine Ipratropium Tiotropium Exogenous Alkaloid Nonselective M Quaternary Ammonium Alkaloid (Atropine Congener) Nonselective M3 Quaternary Ammonium Alkaloid (Atropine Congener) M3 Preoperative reduction of airway secretion Bradycardia Mydriatic for ophthalmic exam DOC to reverse AChE inhibitor or M agonist poisoning Acute asthmatic attack (bronchodilator) DOC for persistent bronchospasm with COPD Closed angle glaucoma (increases IOP) Acute MI Bladder or UT obstruction GI obstruction/ileus Prominent dose response hierarchy Renal excretion Long-term bronchodilation in COPD Biliary excretion after metabolism by CYP3A4 Oxybutinin Synthetic Alkaloid M3 Increase urinary retention (relaxes detrussor) with urge incontinence secondary to neuroegenic bladder Closed angle glaucoma (increases IOP) Toxic megacolon Ulcerative colitis Bladder or UT obstruction GI obstruction/ileus Much more potent antispasmodic activity than atropine GANGIOLINIC ANTAGONISTS Mecamylamine Alkaloid (Gangionic) NN Moderate – severe hypertension Tourette’s Syndrome ARs determined by predominant autonomic tone Trimethaphan Quaternary S+ (Gangionic) NN Hypertensive crisis Aortic dissection Autonomic hyperreflexia ARs determined by predominant autonomic tone Does not cross BBB NEUROMUSCULAR BLOCKERS (NON-DEPOLARIZING) Tubocurarine Benzolisoquinoline Dimer Competitive NAchR Antagonist Atracurium Cisatracurium Benzolisoquinoline Derivative Competitive NAchR Antagonist Mivacurium Benzolisoquinoline Derivative Competitive NAchR Antagonist Pancuronium Vecruonium Rocuronium Rarely used Increase surgical exposure Intubation Maintenance of skeletal muscular paralysis during surgery Blockade of ganglionic nicotinic receptors (tachycardia and hypotension) Blockade of M2 (tachycardia) Tubocurarine and Pancuronium Histamine release Tubocurarine and Pancuronium Antagonism of M2 receptors Pancuroniuma and Rocuronium Aminosteriod Derivatives Competitive NAchR Antagonist Slow renal excretion Spontaneous hydrolysis in plasma (Hoffman elimination) Hydrolysis by plasma ChE. Hydrolysis by plasma ChE only. Transformation in liver results in active metabolites Pancuronium requires renal excretion Vecuronium and rocuronium are exreted into the biliary system NEUROMUSCULAR BLOCKERS (DEPOLARIZING) Succinylcholine Acetylcholine Congener Maximal Agonist (Phase I) Competitive Antagonist Rapid sequence intubation (e.g. with high risk of gastric aspiration) Permits rapid reversal of blockade Myalgia Hyperkalemia secondary to receptor spreading Clearance depends on concentration and activity (Phase II) Risk factors are denervation (demylinating disease, cord lesion, stroke), myopathy, immobility Increased ICP and IOP Histamine release of plasma cholinesterase (e.g. K-variant, atypical variant) Stimulation of ganglionic nicotinic receptors (bradycardia and hypertension) Depolarizaiton of M2 (bradycardia) CHOLINERGIC VESICULAR PACKAGING INHIBITORS Botulinim Toxin A Zinc Protease Cleaves SNAP complex Botulinum Toxin B Zinc Protease Cleaves synaptobrevin Achalasia Hemifacial spasm Spasmodic torticollis Strabismus Cervical dystonia Spasticity, dysphonia, hyperhydrosis, blepherospasm Cervical dystonia ADRENERGIC AGONISTS (DIRECT) Phenylephrine Catacholamine Analogue α1 Nasal Decongestant (pressor effect) Mydriadic (ophthalmic exam) INCREASE MABP DECREASE HR (CI Reflex) Hypovolemic Shock Hypotension Narrow-angle glaucoma Arrhythmia, CVD Hypertension, Tachycardia Labor INCREASE MABP DECREASE HR (CI Reflex) Metabolized by MAO Norepinephrine Natural Catacholamine α1, α2, β1 Epinephrine Isoproterenol Natural Catacholamine α1, α2, β1, β2 Catacholamine Analogue β1 and β2 Bronchodilation (Anaphylaxis) Mydriatic Prolongation of local anesthesia (prevents vascular absorption) Stimulate conduction in AV nodal block Acute bronchospasm Asthma and COPD Albuterol Catacholamine Analogue β2 Rapid bronchidilation (asthma and COPD) Dobutamine Catacholamine Analogue β1 > β2 Catacholamine Analogue α2 Intraoperative treatment of CHF (Increases ventricular contractility and CO) Hypertension Intrathecal injection for refractory opioid pain Clonidine Salmeterol Catacholamine Analogue β2 Tertubaline Catacholamine Analogue β2 Prophylactic treatment for asthma Prophylactic treatment for acute bronchospasm in COPD Rapid bronchidilation INCREASE SYSTOLIC BP DECREASE DIASTOLIC BP BIPHASIC MABP (increase, then drop below baseline) INCREASE HR COMT and MAO Narrow-angle glaucoma Intra-arterial administration Hypovolemic Shock Labor (fetal anoxia) INCREASED CO (increased contractility and HR) DECREASED MABP COMT Arrhythmias Heart block due to Digoxin toxicity DECREASE BP (there are someβ2Rs in vascular smooth muscle) INCREASE HR (CA Reflex) NO EFFECT ON BP COMT and glucoronidaiton Abrupt discontinuation (causes rapid development of hypertension) Breastfeeding Does not treat acute asthmatic bronchoconstriction ADRENERGIC AGONISTS (MIXED) Ephedrine Catacholamine Analogue Mixed Agonist α1, β1, β2 Long-acting Bronchodilator (asthma) PNS actions are diminished by reserpine Increase NE release Not metabolized by COMT or MAO Metaraminol Catacholamine Analogue Mixed Agonist α1 Treatment and prevention of hypotension Increases NE release ADRENERGIC AGONISTS (INDIRECT) Amphetamine Catacholamine Analogue Inhibition of uptake transporter α1 and β1 ADHD Narcolepsy Anorexia nervosa Advanced arteriosclerosis, CAD Hypertension MAO inhibitors Renal excretion after transformation by CYP and MAO. Abrupt discontinuation Renal insufficiency Intrinsic sympathomimentic activity (ISA) INCREASE HR (CA Reflex) Orthostatic hypotension Bolus of NE administered immediately can reverse PBA binding ADRENERGIC AGONISTS (PARTIAL) Acebutolol Pindolol Catacholamine Analogue β1 Catacholamine Analogue β1 and β2 Hypertension Heart Failure Hypertension Angina α-ADRENERGIC ANTAGONISTS Phenoxybenzamine Irreversible α-adrenergic antagonist (PBA) α1 >> α2 Phentolamine Prazosin Yohombine Reversible α-adrenergic antagonist α1 and α2 Reversible α-adrenergic antagonist α1 Reversible α-adrenergic antagonist α2 Control of excessive sweating and hypertension secondary to pheochromocytoma Treatment of urinary obstruction secondary to BPH (relaxes trigone sphincter) Peripheral vasospastic pathology (e.g. acrocyanosis, Raynaud’s disease) Threat sudden hypertension during surgical resection of pheochromocytoma Prevent dermal necrosis secondary to extravasation Hypertension Off-label: urinary retention due to BPH (relaxes bladder outlet) Erectile Dysfunction Large increase in HR (Reflex) First-dose syncope Orthostatic hypotension INCREASE MABP INCREASE HR β-ADRENERGIC ANTAGONISTS Atenolol Metoprolol Propranolol Timolol Cardioselective β-adrenergic antagonist β1 Cardioselective β-adrenergic antagonist β1 Hypertension Heart failure Non-selective β-adrenergic antagonist β1 and β2 Hypertension, Angina, Tachycardia Acute MI (decrease oxygen demand of myocardium) Anxiety Non-selective β-adrenergic antagonist β1 and β2 Hypertension Angina DOC for open-angle glaucoma (decreases IOP in the anterior chamber by inhibiting secretion from the ciliary body) Abrupt discontinuation (causes sudden ischemic injury) Bradycardia AV nodal block Raynaud’s Disease Bronchospasm Insulin-dependent DM (hypoglycemia) Abrupt discontinuation (causes sudden ischemic injury) Bradycardia AV nodal block Raynaud’s Disease Bronchospasm Insulin-dependent DM (hypoglycemia) SYNTHESIS, RELEASE, and UPTAKE MODIFIERS α-Methyltyrosine α-Methyldopa Reserpine Paroxetine Catecholamine Biosynthesis Inhibitor Tyrosine Hydroxylase Catecholamine Biosynthesis Inhibitor Araomatic Amino Acid Decarboxylase False Neurotransmitter α2 (in brainstem) Neurotransmitter Storage Inhibitor VMAT-2 Catecholamine Reuptake Inhibitor Pheochromocytoma (preop or chronic) Alcohol DOC for hypertension during pregnancy Pheochromocytoma (preop or chronic) Historically significant antihypertensive Major depression Anxiety disorders MAO inhibitors (may provoke serotonin syndrome) Major mode of excretion is renal Major mode of excretion is renal Atomoxetine Cocaine Dantrolene Phenylzene Specific to Serotonin Post-traumatic stress disorder Catecholamine Reuptake Inhibitor Specific to Norepinephrine Catecholamine Reuptake Inhibitor Serotonin, Dopamine, Norepinephrine Plasma Membrane Hyperpolarizing Agent Excitation-Contraction Decoupling Agent No-stimulant treatment of ADHD Irreversible MAO Inhibitor Major depression Anxiety disorders Surgical use: diminish congestion, bleeding, and hyperemia Applied locally DOC fro malignant hyperthermia (complication of succinylcholine) Mucosal injury at site of application Blocks Ca2+ release from the SR DRUGS OF THE CARDIOVASCULAR SYSTEM ACE INHIBITORS Drug (Generic Name) Captopril Class, Mechanism Receptor Activity ACE inhibitors Prevents formation of AngII Prevents degredation of Bradykinin Actions and Therapeutic Uses Hypertension Renal protection in diabetics with proteinuria (DOC) Systolic Heart Failure (reduce afterload) USED IN CONJUCTION WITH DIURETIC OR CCB Enalapril Linisopril Increase sodium secretion (direct + aldosterone) Vasodilation AR Absolute Precautions Pregnancy Orthostatic hypotension Decrease renal perfusion Hyperkalemia (aldosterone) ACE cough (bradykinin → PG) Angioedema / Laryngeal edema Clearance, Metabolism, other Remarks Causes left-shift of autoregulatory response: normal flow can be maintained to vascular beds with low pressure. NO RELFEX TACHYCARDIA NSAIDs reduce efficacy Selective dilation of efferent glomerular arteriole ANGIOTENSIN II RECEPTOR ANTAGONISTS (ARBs) Losartan Valsartan Candesartan Competitive antagonists at AT1 receptors Hypertension USED IN CONJUCTION WITH DIURETIC Equivalent actions to ACE inhibitors. Blocks all sources of AngII. Pregnancy Orthostatic hypotension Hyperkalemia Renal impairment Note that the cough and angioedema are rarely seen with ARBs. Pregnancy Orthostatic hypotension Hyperkalemia Renal impairment AngI can be generated by pathways independent of Renin. Thus, ARBs actually potentiate the effect of Aliskerin. RENIN INHIBITORS Aliskerin Competitive antagonist of Renin Prevents formation of AngI Hypertension NITROVASODILATORS Nitroglycerin Isosorbide Dinitrate (ISDN) Organic Nitrates Decay to NO requires reaction with tissue thiols NO → GC → increase cGMP → PKG → SMC relaxation Angina Pectoris Acute Coronary Syndrome (UA, NSTEMI, STEMI) Treatment of HTN requires high doses! Selective dilation of coronary collaterals Venous > Arterial vasodilation Susceptible to tachyphylaxis (requires long maintenance dose interval) Headache Flushing Palpitations Orthostatic Hypotension Interactions with DHP CCBs, Diuretics, β-blockers, PDE inhibitors (potentiation of NO) Reduces preload Reduces CO → reduced afterload Amyl Nitrate Organic Nitrite Nitroprusside Oxidation of HbFe2+ to HbFe3+ (methemoblibin) Direct NO donor CN poisoning Reversal of Nitroprusside toxicity Hypertensive Crisis (acute HF, malignant HTN) Usually administered with thiosulfate to sequester CN CN toxicity Does not require carriage of NO by thiols Arterial > Venous vasodilation Requires constant BP monitoring DIRECT ARTERIAL VASODILATORS Hydralazine Direct Arterial Vasodilator Most selective to renal arteries No effect on skeletal muscle or cutaneous arteries Involves increased production of PG Hypertension DOC for patients with renal insufficiency CHF Tachycardia Possible exacerbation of angina Headache Palpitations Orhtostatic Hypotension Acetylated in hepatocytes Decreased fluid retention compared to other vasodilators CALCIUM CHANNEL BLOCKERS (DIRECT VASODILATORS) Amlodipine Nifedipine Nimodipine Dihydropyridine (DH) Calcium Channel Blockers (CCB) Blockade of L-type calcium channels in vascular smooth muscle Does not require intracellular signal Hypertension Angina Pectoris (selective dilation of coronary arteries) Hypertensive crisis Headache Palpitations Orhtostatic Hypotension Peripheral edema (due to hyperemia secondary to arterial dilation) Exhibits use-tolerance: Most effective with greater L-type Ca2+ opening probability. Loss of potency as channels adopt a closed state. Hypertension Angina Pectoris (reducedO2 demand and increased supply) Orthostatic Hypotension GERD (relaxation of UES) Bradycardia (SA) Heart block (AV) Reduced systolic function (exacerbation of CHF) No tachycardia since sympathetic reflexes are diminished Fluid retention Decreased renal perfusion → activate RAAS Tachycardia Palpitations Increased hair growth Usually administered with a loop diuretic (e.g. furosemide) Arterial >> Venous vasodilation Diltiazem NO EFFECT on visceral SM or conducting myocytes Non-Dihydropyridine (DH) Calcium Channel Blockers (CCB) Selective to cardiac L-type Verapamil Block L-type and T-type channels → reduces automaticity, contractility, and AV conduction Decreased fluid retention compared to other vasodilators Reduces GI and other SM motility POTASSIUM CHANNEL AGONISTS Minoxidil Diazoxide Agonist at leak-type K+ channels Hyperpolarize RMP → reduced entry of Ca2+ through L-type channels → vasodilation Hypertension Diazoxide only used in hypertensive crisis Orthostatic Hypotension Diazoxide inhibits insulin secretion Hyperglycemia DRUGS OF LIPID METABOLISM LDL-C SUPPRESSORS Drug (Generic Name) Atorvastatin Lovastatin Simvastatin Rosuvastatin Pravastatin Fluvastatin Colestipol Cholestyramine Colesevelam Ezetamibe Sterols Stanols Class, Mechanism Receptor Activity Statins Inhibit HMG-CoA reducase → decrease intracellular free cholesterol → decrease VLDL secretion and →upregulation of LDL-R expression → decreased serum LDL-c Bile Acid Resins Bind BAs → reduce uptake of cholesterol derivatives → increased LDL-R synthesis → decrease plasma LCL-C Increased conversion of intracellular cholesterol to BAs → activate HMG-CoA reductase Competitive inhibitor at enterocyte sterol transporter Inbibits absoption of dietary cholesterol and bile salts → increase LDLR expression Plant cholesterol analogues → competitively inhibit the Actions and Therapeutic Uses DOC for elevated LDL-C Decreased TG → decrease VLDL-C Possible due to increased uptake by LDL-R and decreased secretion Slight increase in HDL-C Also TX highly elevated LDL-C with TG < 400 mg/dL Decrease LDL-C Potentiated when used concurrently with a statin or niacin Increased TG due to increased VLDL secretion AR Absolute Precautions AR: rhabdomyolysis when combined with gemfibrozil, transient rise in hepatic transaminase levels Clearance, Metabolism, other Remarks All statins except pravastain are metabolized and inactived by CYP450. CI: pregnancy Inhibited transformation via CYP450 if concurrent with macrolide antibiotics (erythromycin), cyclosporine, diltiazem, verapamil AR: bloating, constipation, sequestration of anionic and amphipathic lipid-soluble drugs (thyroxine, digoxin, coumadine, furosemide) and Vit A, D, E, K. Most effective during meal (with bile acid release) Decrease LDL-C when not responsive to statins Decrease TG Monotherapy with stain intolerance Lowed LDL-C Minimal absorption Hepatic inactivation However, only 10% of drug is present systemically Psyllium (Fiber) intestinal sterol transporter → reduced cholesterol absorption Soluble Fiber Small reduction in LDL-C Weak BA sequestrant (forms micelles) TG Suppressors Niacin (Nicotinic Acid, B3) VitB3 Decreases TG in VLDL Increases HDL-C Inhibits lipolysis at extrahepatic tissues → decreased FFA presentation to liver → decrease TG synthesis → decreased VLDL production Increased VLDL uptake Decreased HDL-C clearance AR: niacin flush (blunt with NSAIDs), pruritis, GI distress, hyperglycemia, uric academia Heaptic metabolism Time-release: high risk of hepatitis Inhibit synthesis of TGs in hepatocytes Fibrates Gemfibrozil Fenofibrate EPA/DHA Reduction of VLDL synthesis → large reductions in TG DOC doe severe hypertriglyceridemia (TG > 300 mg/dL) Chylomicronemia syndrome Prevention of pancreatitis Acts via PPARs Decrease lipolysis Increased CMR clearance Increased LPL activity Decreased cholesterol and BA Synthesis Decreased VLDL Increased HDL-C Omega-3 FAs Slight decrease in VLDL Reduces VLDL production AR: rhabdomyolsis when gemfibrozil iscombined with a statin The only lipid drug with mixed renal and hepatic clearance! Relative CI in renal insufficiency DRUGS OF THE CARDIAC CONDUCTION SYSTEM CLASS I : SODIUM CHANNEL BLOCKERS Drug (Generic Name) Procainamide Class, Mechanism Receptor Activity CLASS IA Actions and Therapeutic Uses Block fast Na+ channels (intermediate recovery rate): Slows AP conduction velocity selectively in ischemic myocardium Suppress ectopic foci (decrease threshold) Blocks delayed rectifier K+ channel: Prolongation of APD and refractory period Slows AV node conduction AR Absolute Precautions AR: slow AV node conduction, hypotension (ganglionic block + reduced contractility) Clearance, Metabolism, other Remarks ECG: Increased QT +widened QRS CI: prolonged QRS, prolonged QT interval, AV block, escape rhythm, heart failure TX: DOC for WPW and WPW + Afib Slows conduction velocities through accessory pathways (e.g. bypass tracts in WPW) Lidocaine CLASS IB Maintain sinus rhythm Block fast Na+ channels (rapid recovery rate): Slow conduction in ischemic myocardium Suppresses ectopic foci AR: CNS effects CI: amide anesthetic hypersensitivity ECG: no visible changes CI: AV block, BBB without pacemaker, cardiogenic shock, structural heart disease, CAD, post-MI ECG: Increases PR interval (due to slowed AV conduction) and widens QRS APD prolongation is not singnificant, so no increase TX: DOC for post-MI VTach Not effective in AVNRT and PSVT (does not increase APD) Flecainide CLASS IC Block fast Na+ channels (slow recovery rate): Slow conduction in ischemic myocardium Suppresses ectopic foci Block delayed rectifier and transient K+ channels : Prolongation of APD and refractory period Slows AV node conduction in QT interval Slows conduction velocities through accessory pathways (e.g. bypass tracts in WPW) CAST Trial: increased mortality when used after MI. DOC for reentrant atrial tachycardias, Afib, atrial flutter, and WPW Maintain sinus rhythm CLASS II : β-BLOCKERS Propranolol Non-selective β-antagonist Decreases cAMP → decrease L-type Ca2+ channel and fNa+ channel permeability → Slows AV node conduction Decreases Phase 4 diastolic depolarization rate → decreases nodal automaticity TX: Atrial flutter, Afib Pheochromocytoma Improved survival post-MI (prevention of arrhythmias) ECG: increased R-R (slowed sinus rate), increased PR No changes in QRS or QT AR: CNS effects, hypotension CI: reactive airway disease (COPD + asthma), insulin-dependent DM Severe sinus bradycardia, AV block, hypotension Not DOC in WPW since it may increase conduction through accessory pathway Esmolol Cardioselective β-antagonist IV in emergent tachyarrythmias Afib, SVT, acute arrhythmias during surgery Metoprolol Cardioselective β-antagonist Similar effects to propranolol Rapid hydrolysis by plasma esterases → short action No biliary or renal clearance. CLASS III : APD EXTENDERS Dofetilide Pure Class III DR K+ inhibitor Blocks DR K+ current (rapid phase, IK+r): Prolongs APD and associated refractory period Slows nodal automaticity (prevents repolarization) AR: TDP secondary to excessive QT length. CI: Baseline prolonged QT, prior episode of TDP, polypharmacy with ECG: QT interval prolonged independently May be used in CHF! TX: Afib, Aflutter Reentrant ventricular tachycardia (PSVT) Amiodarone Maintain sinus rhythm Block fast Na+ channels Decreased SA nodal automaticity Decreases HP conduction velocity Blocks DR K+ current (rapid and slow phases): Increased APD Mixed Classes I - IV DR K+ inhibitor Na+ channel blocker L-type and T-type CCB β-adrenergic blocker other drugs that increase QT (increase APD) AR: pulmonary fibrosis, hyperthyroidism, hepatitis (ECG: Prolonged QT, Prolonged PR, Increased RR, Widened QRS) CI: severe sinus bradycardia or escape rhythms, AV block without pacemaker Block DHP channels + β1R Decrease AV node conduction velocity TX: stable Vtach, Vfib and Vtach resistant to electrical cardioversion, Agib, Aflutter, WPW, AVRNT Sotalol Mixed Class II + Class III d-Sotolol has pure DR K+ antagonistic activity l-Sotolol has pure β-blocking activity Maintain sinus rhythm Β-blockade Reduce nodal automaticity Decreased AV conduction velocity DR-K+ (rapid) blockade Increased APD duration and refractory period in atria and ventricles AR: TDP CI: reactive airway disease, long QT, hypokalemia ECG: increased R-R interval, increased PR and QT TX: Aflutter, WPW Vtach Afib AVRNT Maintain sinus rhythm CLASS IV : NON-DIHYDROPYRIDINE CALCIUM CHANNEL BLOCKERS Verapamil Non-DHP CCB Blocks L-type Ca2+ channels in myocardium and vascular SM Slows Phase 4 depolarization in SA node Decreases AV node Slows ventricular rate with Afib or Aflutter AR: headache, flushing, hypotension NO reflex tachycardia CI: systolic heart failure (depressed contractility), post-MI, severe bradycardia, AV block ECG: increased PR sue to slow AV conduction velocity TX: Afib and Aflutter (ventricular rate control) Ectopic + multifocal atrial tachycardias Chronic AVNRT WPW Diltiazem Non-DHP CCB Very similar to verapamil AR: same as verapamil + bradycardia CI: systolic dysfunction CLASS V : OTHERS Digoxin Cardiac Glycoside: Positive Inotrope Inhibits cardiac and ganglionic Na2+/K+ ATPase Causes increased intracellular Na+ and Ca2+ (via gradient inhibition of the Na+/Ca+ exchanger) Stimulates carotid and aortic sinuses (baroreceptors) → increased vagal tone to SA and AV Slows Phase 4 depolarization in the SA node Decreases conduction velocity though AV node Depolarization (increased Na+) and accommodation of t-type Ca2+, L-type Ca2+ and Na+ channels L-type Ca2+ is activated in late in Phase 4 AR: AV block, sinus bradycardia, digoxin toxicity → Ca2+ overload and delayed ADs (triggered Vtach). ECG: increased PR, decreased HR CI: sinus bradycardia, AV block, WPW (increases conduction through accessory path) Increases AV node refractory period Decreased intracellular K+ (dissipated gradient) Decrease AV node automaticity Vagal tone and decreased K+ gradient TX: DOC for Afib and Aflutter (atrial rate control) with LV systolic dysfunction AVNRT Adenosine Endogenous Purinergic Agonist Binds A1 purinergic receptors → Gi → βγ subunit→ increased permeability K+ channels (similar to Ach mechanism) Shortened APD Hyperpolarization → slowed automaticity Inhibits AC → decrease cAMP from β agonists Decreases permeability of L-type and RyR Ca2+ channels Decreased intracellular Ca2+ AR: Flushing, dyspnea, sinus arrest CI: sinus bradycardia, AV block, reactive airway disease ECG: decreased HR, increased PR Slowed Phase 4 depolarization of SA node Decreased conduction through AV node Increased AV refractory period TX: AVNRT and WPW (acute cardioversion) DRUGS USED IN THE TREATMENT OF HEART FAILURE DIURETICS Drug (Generic Name) Furosemide Bumetinide Torsemide Class, Mechanism Receptor Activity Loop Diuretics Inhibit Na+/2Cl-/K+ cotransporter in ATL of LoH Hydrochlorothiazide Thiazide Diuretics (Spirinolactone) Inhibit Na+/Cl- cotransporter in DCY K+-sparing Diuretic Inhibits aldosterone receptor in DCT (downregulate Na+ conductance channel) Actions and Therapeutic Uses in Heart Failure Diuresis of fluid overload This decreases preload without a decrease in CO (in advanced systolic failure) Tolerance: TG feedback (increased Na+ reaborption in DCT and CD with prolonged therapy) Decreased renal perfusion (volume depletion, decompensation with loss of CO, ACEIs) Used at onset of tolerance to loop diuretics Advanced heart failure AR Absolute Precautions AR: hypokalemia, hypochloremic alkalosis (supplement K-sparing diuretic) Hyperglycemia Clearance, Metabolism, other Remarks RAAS antagonists actually compensates via inhibition of aldosterone (decreased K+ secretion) AR: gynecomastia Shown to decrease mortality in advanced SHF unresponsive to adrenergic blockers and other diuretics VASODILATORS Lisinopril ACE inhibitor Arterial and venous vasodilation Decreased afterload → increase SV and EF Decrease venous return → decreased EDV Valsartan ARB Similar effects to ACEIs Inhibits ectopically produced AngII Venous vasodilation Reduced preload Epicardial coronary artery dilatation → increase CBF, increase systolic and diastolic function Shown to decrease mortality Not used in DHF Nitroglycerin Organic Nitrate Susceptible to tolerance ARs: orthostatic hypotension, tachycardia, palpitaitons, flishing, headache Shown to decrease mortality when coformulated with hydralazine. Hydralazine Nitroprusside Nesiritide Direct Vasodilator Direct NO donor Recombinant BNP Arterial vasodilation Reduces pulmonary vascular resistance (PVR) → decreased preload on RV and LV Used in CHF with renal insufficiency (preferentially increases renal arterial perfusion) Parenteral Arterial > venous vasodilation Reduces preload and afterload Parenteral Bind to soluble GC → increase cGMP → vasodilation AR: similar to nitrates CN toxicity AR: hypotension TX: bolus of continuous infusion for acute heart failure (dyspnea at rest or minimal exertion) ADRENERGIC ANTAGONISTS Carvedilol Metorpolol Non-selective β antagonist α1 antagonist Cardioselective β antagonist Prevents adrenergic stimulation of ventricular remodeling. Transient suppression of contractility Prevention of ventricular arrhythmias associated with ischemia and hypertrophy CI: rapid titration (may lead to decompensation) Increase EDV and EF Bisoprolol Prazosin Cardioselective β antagonist Must be titrated from a very low concentration (10fold lower than therapeutic dose) α1 antagonist Arterial and venous vasodilation Reduced afterload CALCIUM CHANNEL BLOCKERS Amlodipine Transient decrease in systolic function. Gradual recovery and improvement due to prevention of adverse neurohormonal remodeling. Shown to reduce mortality due to Vfib. Second-generation DHP CCB Arterial vasodilation (highly selective) Used when hypertension cannot be controlled with other drugs TX: diastolic heart failure (use first-generation CCBs) Heart failure due to SVT without systolic dysfunction CI: use of first-generation CCBs in systolic dysfunction (verapamil, diltiazem, nifedipine) causes a severe reduction in inotropy INOTROPES Milrinone Digoxin PDE inhibitor Cardiac Glycoside Inhibits PDE3 in myocardium and vascular SM In cardiac muscle: → increased PKA → increased L-type Ca2+ channel permeability → increased contractility In vascular SM: → increased PKA → activate K+ channels → hyperpolarization → relaxation TX: acute heart failure Actually increases mortality Increases intracellular Ca2+ Inhibit sacrolemmal Na+/K+ ATPase → increased intracellular Na+ → gradient inhibition of Na+/Ca2+ exchanger (Na+ is normally transported into the cell) → increased intracellular Ca2+ → increased sequestration in SR → increased CICR → increased contractility Increased permeability of RyR channels Na+/Ca2+ may actually reverse direction during AP → Ca2+ transported into cell Positive inotropy Negative chronotropy at AV node (dissapte K+ gradient → prolonged repolarization and refractory period) Sensitive autonomic ganglia → increase vagal tone → reduce AV conduction velocity End result: Increase CO → decrease neurohormonal compensation AR: ventricular arrhythmias, extopy, Vtach, hypotension AR: narrow therapeutic margin, triggered arrhythmias (delated Ads) Interactions Increased binding with hypokalemia (inhibited Na+/K+ ATPase) Quinidine reduces the volume of distribution of Digoxin by displacing it from non-target binding sites Potentiated by drugs that decrease nodal automaticity and conduction Dobutamine β1and β2 agonist Parenteral Circulatory support in acute heart failure AR: tachycardia, tolerance Increased contractility Decreased SVR (racemic formulations do not cause vasoconstriction) Dopamine Endogenous catecholamine Parenteral Low dose (renal): DA1 receptors in renal vessels → increased RBF → increased GFR → natruiresis Inhibits tubular Na+ reabsorption Intermediate dose (cardiac): β1 receptors → increase CO and MABP Also triggers NE release from sympathetic axons High dose (vascular): α1R → vasoconstriction AR: tachycardias, arrhythmias, ischemia with CAD DRUGS OF AUTOCOID METABOLISM ANTIHISTAMINES: H1 RECEPTOR ANTAGONISTS Drug (Generic Name) Diphenhydramine Chlorpheniramine Class, Mechanism Receptor Activity First-Generation H1 Antagonists (competitive) Non-selective to H1R Hydroxyzine Fexofenadine Loratidine Second-Generation H1 antagonists (competitive) Selective to HIR Actions and Therapeutic Uses Allergic Rhinitis Do not alleviate congestion (requires direct vasoconstrictor) Urticaria Allergic conjunctivitis Motion sickness (CAN anticholinergic effects) Sedation Parkinsonism AR Absolute Precautions Sedation Anticholinergic effects Teratogenicity Allergic Rhinitis Urticaria Allergic conjunctivitis Sedation Clearance, Metabolism, other Remarks Metabolized in liver Inherit ethylamine moiety from histamine Production of active metabolites Inherit ethylamine moiety from histamine Desloratidine Ceterizine ANTIHISTAMINES: H2 RECEPTOR ANTAGONISTS H2 antagonists (competitive) Cemetedine Ranatidine Famotidine Blocks H2 receptors on serosal membranes of parietal cells Gastric and duodenal ulcers GERD Cimtidine : gynecomastia (M), galactorrhea (F) Inherit imidazole moiety from histamine Nizatidine HISTAMINE RELEASE INHIITORS Cromolyn Sodium Histamine Release Inhibitor Asthma (inhaled) Allergic and vernal conjunctivitis Hyperpolarization → decrease degranulation of mast cells HISTIDINE SYNTHESIS INHIBITORS α-F-Me-Histidine Inhibitor for His decarboxylase Allergic rhinitis Peptic ulcer GLUCOCORTICOIDS Glucocorticoids Prednisone Fluticasone Decrease COX-2 gene expression Decrease expression of cytokines involved activation of COX-2 Increase lipocortin synthesis → inhibit lipolysis by PLA2 → decrease free arachidonic acid Eosinophil apoptosis RA, Gouty Arthritis SLE Dermatoses Alligraft Rejection IBD (UC, Crohn’s) HRT in Addison’s disease Dermatoses Psoriasis Allergin + nonallergic rhinitis Asthma prophylaxis AR: weight gain, suppression of HPA, slowed wound healing, opportunistic infections Oxidized by CYP3A4: generates the active metabolite (predisolone) CI: Cushing’s, abrupt discontinuation AR: pruritis, hypertrichosis, erythema, slowed wound healing, weight gain, HPA suppression No active metabolites CI: Cushing’s, abrupt discontinuation NON-OPIATE ANALGESIC (NOT AN NSAID) Acetominophen (APAP) COX-3 inhibitor Increases pain threshold via inhibition of Substance P TX: Analgesia in geriatric patients with chronic pain, or when aspirin is contraindicated Has antipyretic and analgesic activity No anti-inflammatory effects! ARs Analgesic nephropathy (similar to renal dysfunction seen with all NSAIDs) Hepatic Toxicity CYP2E1 → converts APAP to NAPQI → covalent biding to subcellular structures → fatal hepatic necrosis TX with N-acetylcysteine (restore glutathione reservoir) EtOH increases CYP2E1 expression. It also decreases glutathione levels. Thus, it increases production of NAPQI with APAP. NONSELECTIVE NSAIDs Acetylsalicylic acid Aspirin Choline Magnesium Trisalicylate Irreversible (covalent) inhibition of COX-1 and COX-2 Acetylataiton of Ser in the active site Nonacetylated Salicylates Salsalate Diflunisal Ibuprofen Ketoprofen Naproxen Propprionic acids Acetic acid derivatives Diclofenac Etodelac Ketorelac Indomethacin Enolic Acids Meloxicam Nabumetone Analgesic Inhibits PG synthesis → decrease response of central afferents to Glu and Substance P AND desensitization of peripheral nociceptors Antipyretic Inhibit PG synthesis → hypothalamic nuclei → peripheral vasodilation → dissipation of heat Anti-Inflammatory Reduced synthesis of PG and TXA2 Regulation of Platelet Agglutination Only mixed inhibitors reduce aggregation (platelet do not have COX-2) Occurs at low doses only (75 – 81 mg/d) High doses lead to GI bleeding Thus, COX-2 inhibitors are used concurrently with aspirin to reduce risk Aspirin can be used as an antithrombotic since it causes irreversible inhibition Reduced uterine contraction Alleviates spasm in dysmenorrheal Nociceptive and inflammatory pain Analgesic ceiling Rheumatoid Arthritis PGE2 synthesis is upregulated in the synovium Dysmenorrhea Decreased synthesis of PGF in the myometrium Gout Not DOC for analgesia in geriatric patients due to increased risk of GI bleed Use APAP Diclofenac can be administered transdermally GI Hemorrhage Decreased PGE3 synthesis → acidification of the GI lumen → increased risk of ulceration and perforation RFs: > 65 years, previous GI event, corticosteroid taper, SSRIs, antiplatelet therapy, alcohol, smoking Thus, non-selective NSAIDs are combined with misoprostol or PPI. Decreased risk with COX-2. Decreased Renal Function COX-1 and COX-2 are concentrated in renal tissue and indispensable for normal function Aspirin Intolerance Generated by all nonselective NSAIDs COX-1/COX-2 inhibition → increase flux through 5-LOX pathway → increased synthesis of CysLTs → anaphylactoid reaction For patients with Aspirin-Sensitive Respiratory Disease TX with COX-2 inhibitors Bronchospasm, urticaria, shock Vascular COX-2 → decreased PGI2 synthesis without decreased TXA2 synthesis → increased thrombosis CI: pregnancy (late), febrile pediatric patients (COX-2) SELECTIVE NSAIDs Celecoxib Selective inhibitor TX: use in ASRD and patients with high risk of GI bleed PROSTANOID AGONISTS Alprodastil PGE1 analog Latanoprost Relaxation of the trabecular smooth muscle Dilates arteries supplying the corpus cavernosum PGF2α analog Erectile dysfunction Maintains patency of ductus arteriosus (continuous infusion) AR: priapism DOC in open-angle glaucoma and intraocular hypertension AR: blurred vision, conjuctival hyperemia, iris pigmentation, epithelial keratopathy, iritis, uveitis FP receptors → increases uveoscleral flow → decreases IOP Misoprostol PGE1 analog EP receptors on parietal cells → Gi → inhibit AC → decrease cAMP → inhibit H+/K+ ATPase → decreased H+ secretion Increases HCO3- secretion Prevents gastric ulcers in patients undergoing chronic NSAID therapy Abortion, following mifepristone (increases amplitude of myometrial contractions and causes dilation of the cervix) CI: history of iritis or uveitis, active intraocular inflammation CI: pregnancy LOX INHIBITOR Zileuton Irreversible 5 –LOX inhibitor Chelates a Fe2+ cofactor Decreases synthesis of all LTs → decreased granulocyte chemotaxis, control of bronchospasm Prophylaxis and chronic TX for asthma AR: hepatotoxicity (requires pretreatment and continued assessment of ALT for length of therapy) LEUKOTRIENE RECEPTOR ANTAGONISTS Montelukast Zafirlukast CysLT1 antagonist (G-protein coupled) → blockade of CysLT actions on the airway and inflammatory cells CysLT1 antagonist (G-protein coupled) → blockade of CysLT actions on the airway and inflammatory cells Chronic TX of asthma Allergic rhinitis CI: acute asthmatic episode Reduces dose when formulated with glucocorticoids Prophylaxis and chronic TX of asthma Less efficacy than fluticasone (inhaled corticosteroid) CI: acute asthmatic episode DRUGS used in the treatment of MYCOBACTERIAL INFECTION FIRST-LINE AGENTS Drug (Generic Name) Isoniazid (INH) Rifampin Class, Mechanism Activity Cidal Drug Inhibits cell wall synthesis INH → isonicotinic acid → inhibit generation of mycolic acid Cidal Drug Inhibits RNA and protein synthesis Effective against intracellular and extracellular infection Rifapentine Actions and Therapeutic Uses Treatment of active TB disease Prophylaxis for LTBI TB meningitis Treatment of active TB disease Prophylaxis for LTBI Leprosy TB meningitis Aliphatic side chain causes conformational distortion of M. tb RNA polymerase Pyrazinamide Cidal Drug Unknown mechanism of action Treatment of active TB disease Requires actively dividing organisms Ethambutol Static Drug Inhibits incorporation of mycolic acid into the cell wall Chelates metals → inhibits protein synthesis Treatment of active TB disease TB meningitis AR Absolute Precautions Delayed Hepatic Toxicity Discontinue if AST > 3 X NML Peripheral neuropathy Prevent by co-treating with pyridoxine (VitB6) Hepatitis RF: chronic liver disease, alcoholism, age Increased CYP450 expression Accelerate metabolism of other drugs (including antiretroviral agents) Arthralgia (70%) Hepatotoxicity CI: any evidence of liver failure Gout CI: Gestation Optic Neuritis Loss of color discrimination (typically reversible) Gout Resistance Pharmacology 6 Resistance rate is 1:10 Missense mutation of InhA gene (mycolic acid synthesis) Distributes into CSF, ascites, and pleural fluid Resistance rate is 1:108 Mutations in β-domain of the RNA polymerase Decrease permeability to drug Distributes to the CSF Some strains lack pyrazinamidase, and do not transform drug into active form If resistant to INH, organisms will not be resistant to ethambutol! Dapsone Requires actively dividing organisms Sulfone Interferes with folate acid synthesis Leprosy GI distress Hemolytic anemia Leukopenia Hepatities Cholestasis SECOND-LINE AGENTS Ethionamide Aminosalicylic Acid Cycloserine Streptomycin Kanamycin Amikacin Inhibits mycolic acid synthesis Used with resistance to first-line drugs or RFs (HIV coinfection) PABA analogue D-Alanine analogue Inhibits cell wall synthesis Aminoglycoside ABx Capreomycin Cyclic peptide Ofloxacin Ciprofloxacin Fluoroquinolone ABx With failed regimes, add > 1 drug class to prevent resistance GI distress Hepatitis GI distress Psychosis Seizures Ototoxicity (sensorineural hearing loss) Nephrotoxicity Ototoxicity Nephrotoxicity GI distress ANTIBACTERIAL DRUGS derived from the β-LACTAM SUBSTRATE PENICILLINS (PCNs) Mechanism of Action (All β-Lactam Drugs) GPOs: diffusion across PG layer GNOs: transport through porin into the periplasmic space → bind PBPs (transpeptidase, carboxypeptidase, endopeptidase) → inhibit transpeptidation of PG → loss of cross-linking → bacterial autolysis Can Tx meningitis due to low toxicity (high therapeutic index and Certain Safety Factor) These are the most allergenic ABx PCN G is acid-labile, so must be administed parenterally (IM) The semisynthetic PCNs are resistant to hydrolysis by β-lactamse. Resistance is conferred by altered PBP (e.g. MRSA, MRSA) Effeciveness is determined by time above the MIC Drug (Generic Name) Class, Mechanism Penicillin VK Penicillin G Natural Penicillins Penicillin G Benzanthine Spectrum and Therapeutic Uses GPOs: streptococci, enterococci, pneumococci, peptostreptococcu, Listeria, Clostridia GNOs: meningococcus Triponema pallidum, Borrelia, Leptospira Nafcillin: Neutropenia Resistance Pharmacology Resistance is due to βlactamase, porin variation, and altered PBPs Peperacillin + Ticarcillin: salt retention Streptococcal pharyngitis and endocarditis Syphilis (Triponema) Gas Gangrene Periodontal Infection PCN G Benzathine reduces clearance rate → increased efficacy against Treponema and Strep Amoxicillin Ampicillin AR Absolute Precautions Hypersensitivity Reactions Aminopenicillins GPOs: same as PCN GNOs: same as PCN + E. coli + Proteus + Haemophilus Respiratory Tract Infections (upper and lower) Uncomplicated UTI Enterococcal infections Listeriosis Crystalline PCN G: IV for endocarditis and brain abscesses PCN VK: resistant to destruction by gastric acid Short half-life Dicloxacillin Nafcillin Oxacillin Methicllin Ticarcillin Piperacillin AmoxacillinClaculanate Semi-synthetics GPOs: Staph and Strep No activity for GNOs, enterococci , and anaerobes These drugs are PCNaseresistant! DOC for Staphylococcal infections Extended Spectrum PCN + β-lactamase Inhibitor AmpicillinSulbactam PiperacillinTazobactam GPOS: streptococci, enterococci (piperacillin) GNOs: aerobes, pseudomonas Short half-life Pseudomonas infections: requires β-lactamase inhibitor Spectrum is equivalent to parent PCN + β-lactamase +ve S. aureus, E. coli, H. influenza, M. catarrhalis, Klebnsiella, and Bacteroides Inhibitors are no antibacterial Respiratory Tract Infections Head and Neck Infections Cellulitis Bite infections Intra-abdominal Infections CEPHALOSPORINS Mechanism: Inhibit cell wall synthesis DOC: CAP and meningitis Generation IV: covers GNOs (pseudomonas) + GPCs with high-level activity against Staph Cephamycins: only group with anaerobic coverage No drugs against enterococci, Listeria, MRSA, ESBL Efficacy is determine by time above MIC Cefazolin Generation I GPOs: GPCs GNOs: E. coli, Klebsiella Streptococcal and staphylococcal skin and soft tissue infections Cross-reactivity with the PCNs Ceftriaxone: biliary sludging Cefepime: non-focal neurologic deficits Resistance is due to βlactamase, porin variation, and altered PBPs Generation II : Cefuroximes Cefuroxime Generation II : Cephamycins Cefoxitin Cefmetazole Respiratory Tract Infection (upper and lower) Equivalent to Generation I + anaerobes + various GNOs Cefexime Ceftriaxone Ceftazadime Intra-abdominal and pelvic infections GPOs: streptococcus GNOs: nearly complete coverage (including pseudomonas: ceftazadime) Generation III Equivalent to Generation I + Haemophilus + Moraxella NO ACTIVITY: Staph Generation IV (Cefepime) Cefepime Meningitis CAP Gonorrhea, UTI Pseudomonas Infections GPOs: Generation I GNOs: Generation III NO ACTIVITY: anaerobes Nosocomial Infections Febrile Neutropenia Pseudomonal Infections UTI CAPBAPENEMS Broad Spectrum Imapenem Meropenem Doripenem Ertapenem Coverage: almost all bacteria NO ACTIVITY: MRSA, methicillin-resistant coagulase – ve staph, enterococcus, Clostridium. ALL EXCEPT Ertapenem have activity against Pseudomonas and anaerobes Severe infection with resistant pathogens Meningitis (Peds) Hypersensitivity Cross-reactions with PCN Imapenem: causes seizures with decreased renal function Resistance is due to βlactamase, porin variation, and altered PBPs Mixed infections (intra-abdominal and soft-tissue) MONOBACTAM Coverage of Gm-ve bacilli No activity against GPOs or anaerobes Aztreonam Hypersensitivity Thus, the spectrum is Gm-ve aerobes (similar to aminoglycosides) Resistance is due to βlactamase Effectiveness is determine by time above MIC DOC for Pseudomonas infection with PCN or other βlactam allergy GLYCOPEPTIDE Vancomycin Binds to D-ala-D-ala dipeptide moiety of the PG precursors → prevents binding of peptidoglycan polymerase (this is the biosynthetic step that precedes cross linking) → bacterial autolysis Covers GPOs Aerobes (including MRSA, MRESE, VRE) and anaerobes Neutropenia Nephrotoxicity Red Man Syndrome NO ACTIVITY AGAINST GNOs! Enterococcal resistance (VRE): modification of the peptidoglycan dipeptide precursor (encoded by VanA) DO NOT USE FOR SYSTEMIC INFECTION (poor GI absorption) VanA gene transferred to S. aureus (VRSA) MRSA + coagulase-negative staphylococcal infections Ampicillin-resistant enterococcal infections Resistant pneumococcal infections (e.g. meningitis) C. diff colitis (oral formulation) Concentrated in GI tract (minimal absorption) Does not cross BBB Slowly cidal ABx Static activity against enterococci, so add aminoglycoside CYCLIC LIPOPEPTIDE Daptomycin Causes rapid membrane depolarization upon binding → loss of membrane potential → inhibition of protein synthesis → bacterial autolysis Covers GPOs Aerobes (including MRSA, MRESE, VRE) and anaerobes NO ACTIVITY AGAINST GNOs! Less toxicity compared to Vancomycin Concentration-dependent response! The cidal activity is more rapid than Vancomycin Emerging therapy for severe MRSA, VRE, and coagulase-negative staphylococcal infections NOT USED FOR PNEUMONIA (inactivated by pulmonary surfactant) ANTIBACTERIAL DRUGS : TRANSLATIONAL INHIBITORS Drug (Generic Name) Class, Mechanism Spectrum and Therapeutic Uses AR Absolute Precautions Resistance Pharmacology AMINOGLYCOSIDES Gentamycin Tobramycin Streptomycin Natural Aminoglycosides (generated by Streptomyces) Oxygen-dependent transport → irreversible binding of 30S ribsosome → inhibits elongation cycle + translational misreading → bacteriocidal activity GNOs: all aerobic Gm –ve bacilli Enterobacteriaciae Some coverage of Staph With combination Tx: Staph, Strep, enterococci Tobramycin has greatest cidal activity against Pseudomonas Streptomycin + Amakacin: Mycobacteria NO ACTIVITY: ANAEROBES! Plague Tuleremia Complicated UTI involving GNR Combination Tx with β-lactams: Pseudomonas, staphylococcal, streptococcal, enterococcal endocarditis The β-lactams destabilize the cell wall and allow greater influx of aminoglycosides into the GPCs Mycobacterial infection Amikacin Semisynthetic Kanamycin + OH-Butyric Acid Nephrotoxicity Binds at the brush border of the apical side (PCT) → pinocytosis → tubular necrosis Preferentially affects renal cortex Saturable kinetics: less tubular uptake with single large dose Ototoxicity (Irreversible) Binds vestibular and cochlear membranes → concentrates in endolymph Concentration-dependent activity Large bolus is preferred regimen of dosing Prolonged effects Resistance Chromosomal mutations: within the ribosomal binding domain Increased efflux: prevalent in Pseudomonas Inactivation: some enzymes encoded by plasmids → acetylation, adenylation, phosphorylation of drug Low volume of distribution due to high water-solubility Low GI absorption Does not cross BBB Renal elimination The OH-Butyric acid moiety inhibits bacterial inactivating transferases TETRACYCLINES Polycyclic antibiotic (four rings): semisynthetic derivatives Doxycycline Minocycline Tigecycline Inhibits binding of activated transfer RNA to the 30S ribosome → bacteriostatic activity Binding is reversible Broad spectrum GPOs: all EXCEPT enterococci GNOs: all EXCEPT Pseudomonas Atypical: Mycoplasma, Chlamydia, Clamydophila, Rickettsia, Spirochetes, Malaria Discoloration of teeth and bones GI distress (NVD) Fungal superfinfection: candidiasis Time-dependent killing (levels > MIC) Prolonged effects Resistance Major mechanism of resistance is increased drug efflux Widespread crossresistance seen with tetracyclines NO ACTIVITY: enterococci and Pseudomonas! Second-line Tx for CAP (including atypicals) Non-specific urethritis, gonorrhea, syphilis Lyme Dz RMSF (Rickettsia) Malaria CA-MRSA infections: minocycline Anthrax prophylaxis and treatment Lipid-soluble: rapid absorption with high Vd. Tigeclycline (IV, glycylcycline) → Tx MRSA and VRE (no efflux and high ribosomal affinity) Currently no resistance to Tigecycline CHLORAMPHENICOL Chloramphenicol Nitrobenzene pole Broad spectrum Binding to 50S ribosome → inhibits peptidyl transferase → cessation of elongation cycle → bacteriostatic activity Binding is reversible NO ACTIVITY: Psuedomonas and Legionella Severe typhoid fever due to Salmonella infection Bacterial meningitis with β-allergy CNS abscess with anaerobic infection Myelosuppression Inhibits host protein synthesis Reversible Aplastic Anema Toxicity to marrow stem cells; thus it is dose-independent Gray Syndrome Seen in neonates Lack of glucoronidation → vascular collapse Resistance Acetylation of the nitro group by Chloramphenicol Acetyl Transferase (CAP); encoded by plasmid Lipid soluble: high bioavailability and Vd MACROLIDES Erythromycin Clarithromycin Azithromycin Natural Macrolide Binds 23S subunit of the 50S ribosome → inhibits attachement of tRNA Binding is reversible Semisynthetic GPOs: streptococci, pneumococci Atypical: Legionella, Mycoplasma, Cglamydia, Chlamydophila, some Mycobacteria GNOs: H. pylori GI distress (NVD) Hepatitis during pregnancy Slow cidal activity Time-dependent activity Prolonged Effects NO ACTIVITY: Staph Respiratory Tract Infection Sinusitis, AOM, exacerbations of chronic bronchitis, CAP (covers atypicals) Streptococcal pharyngitis and cellulitis (PCN-allergy) Atypical Mycobacterial Infection H. Pylori infection (cotreat with PPI and another ABx) Treatment and prophylaxis of Pseudomonas infection in CF No activity against Pseudomonas, but inhibits biofilms Resistance Methylation of the 23S ribosomal subunit Erm genes: pneumococcal resistance in Europe Increased efflux Mef genes: pneumococcal resistance in US Genomic mutation of the 52 ribosome Inactivation GNRs may produce esterases Erythromycin is acid-labile (low GI absorption) The semi-synthetics have improved absoption Concentrated within the pleural fluid LINCOSAMINE Clindamycin Binds 23S ribsosomal subunit → inhibits attachment of tRNA Binding is reversible GPOs: Staph and Strep Anaerobes (including Bacteroides fragilis) NO ACTIVITY: Mycoplasma, Legionella, Chlamydia Equivalent mechanism to the macrolides (same binding site) Supradiaphragmatic anaerobic infections (e.g. lung abscess) Streptococcal infection (Group A) Diarrhea Pseudomembranous Colitis Selects for clindamycinresistant C. difficile → enterotoxins and cytotoxins Lipid soluble: high bioavailability and Vd Staphylococcal infection (CA-MRSA) Toxyplasmosis Pneumocystis STREPTOGRAMINS Dalfopristin (A) Quinopristin (B) Typically coformulated IV only Quinopristin: equivalent action to clindamycin and macrolides Dalfoprisitin: bind to novel 50S site GPOs: virtually all EXCEPT Enteroccocus faecalis Good coverage of Staph, MRSA, Strep, Enterococcus faecium, VRE Only route of administration is IV Resistance Methylation of 23S: quinupristin only → renders combination therapy bacteriostatic Genomic mutation of 23S: dalfoprisitn NOT effected by efflux pumps (MDRD) VRE infections MRSA infections Static when Tx in isolation Cidal when Tx in conjunction Moderate serum levels and tissue distribution OZAZOLIDINONE Linezolid Bind 50S → inhibit congregation of 70S initiation complex GPOs: virtually all Good coverage of Staph, MRSA, MRSE, Strep, pneumococci, enterococci, VRE Static + slow cidal activity VRE infections MRSA infections (DOC for MRSA pneumonia) MRSE infection Thrombocytopeni+ Anemia (> 2 wks) Peripheral neurpathy (> 4 wks) Resistance Seen in E. faecium: genomic mutation of the 50S ribosome High Cost Lipid soluble: high bioavailability and Vd KETOLIDE Telithromycin Derived from macrolides: long alkyl side-chain allows dual binding to a remote sute on 23S ribosome Spectrum is equivalent to macrolides + resistant streptococci and pneumococci GI distress (NVD) Hepatitis during pregnancy DOES NOT COVER Staph! (Note that Staph is resistant Transient loss of visual acuity Slow cidal activity Time-dependent activity Prolonged Effects Equivalent mechanism to macrolides to macolides) Liver failure DOC for CAP with macrolide resistance CI: myasthenia gravis NITROFURANS Nitrofurantoin Synthetic Nitrofuran Nitrofuran → transformed by Nitrofuran Reductase → radicalized derivatives → bind to cytosolic proteins GPOs: enterococci GNOS: E. coli, some Enterobacter and Klebsiella Tx and prophylaxis of UTI GI distress Pulmonary hypersensitivity (pleural effusion, IPF) Rapid spontaneous degradation in the plasma → only attains therapeutic concentrations in urine ANTIBACTERIAL DRUGS : TRANSCIPTIONAL INHIBITORS Drug (Generic Name) Class, Mechanism Spectrum and Therapeutic Uses AR Absolute Precautions Resistance Pharmacology QUINOLONES Ciprofloxacin Inhibit DNA gyrase (Top II) and Top IV Cidal Activity GPOs: Pseudomonas, GPCs (pneumococcus) GNOs: aerobic GNRs Atypicals: Mycoplasma, Chalmydophila, Legionella GEN1 agents (Ciprofolxacin): NO ACTIVITY against GPOs or anaerobes GEN2 agents (Levofloxacin, Moxifloxacin): extend coverage to GPOs Use these for RTIs! Levofloxacin Moxifloxacin Phototoxicity Cartilage damage (animal models) Hepatities Prolonged QTc interval Vertigo Dysglycemia Lipid soluble: high bioavailability and Vd Hepatitis Drug Interactions: increased CYP450 expression → increase clearance of other meds Urine discoloration Resistance Mutations of the β-subinit of DDRNAP. Rifamycin cannot be used alone to Tx M. tb Cannot be administered with divalent cations (e.g. Ca2+, Mg2+) Enteric infection with aerobic GNRs Severe GNO infection Severe Pseudomonas infection RTIs Mycobacterial infection Prostatitis UTIs RIFAMYCINS Rifampin Rifabutin Rifapentine Rifaximin Inhibit DNA-dependent RNA polymerase (DDRNAP) Cidal Activity Broad spectrum Good coverage of Staph, Mycobacteria, ETEC Tx Active TB Prophylaxis and Tx atypical mycobacterial infection Staph osteomyelitis, abscess, endocarditis Prosthesis infections ETEC diarrhea Recurrent C. diff infection METRONIDAZOLE Metronidazole Converted to active metabolite by bacterial nitro reductase → binding and DNA damage Cidal Activity Anaerobes (including Bacteroides) Protozoa: Giardia, Trichomonas vaginalis Peripheral Neuritis Emesis with EtoH intake NO ACTIVITY: aerobes Lipid soluble: high bioavailability and Vd Resistance No expression of nitro reductase Subdiaphragmatic anaerobic infection Bacterial vaginosis C. difficile infection: diarrhea and pseudomembranous colitis SULFONAMIDES Sulfadiazine Lipid-soluble PABA analogue Complexed with Ag2+for topical burn therapy PABA analogue → competitive inhibition of Dihydropteroate Synthetase → no generation of DHF Sulfamethoxazole Broad Spectrum Covers Nocardia, Toxoplasma, Pneumocystis Hypersensitivity Reactions Urine crystals UTI (with TMP) Nocardia infection Toxoplasmosis Pneuocystis pneumonia (with TMP) Burns (silver sulfadiazine Resistance Mutations leading to decreased drug affinity Increased PABA synthesis Decreased Permeability Lipid soluble: high bioavailability and Vd Sulfadiazine crosses the BBB Cidal with TMP Water-soluble PABA analogue TRIMETHOPRIM Trimethoprim (TMP) Inhibits DHF reductase → no formation of THF Highly selective for bacterial isoform of DHF reductase GPOs: Staph, pneumococci (with PCN-susceptibility) GNOs: GNRs NO ACTIVITY: Pseudomonas UTI RTI: exacerbations of chronic bronchitis, sinusitis, AOM Pneumocystis pheumonoa Typhoid fever Enteric infections Folate deficiency Megalobalstic anemia, leukopenia Resistance Mutations resulting in reduced affinity Seen in GNRs and pneumococcus Lipid soluble: high bioavailability and Vd CA-MRSA DRUGS used in the TREATMENT OF FUNGAL INFECTIONS POLYENE ANTIFUNGALS Drug (Generic Name) Amphotericin B Class, Mechanism Polyene Plasmalemma Inhibitor Spectrum and Therapeutic Uses Fungicidal against most pathogenic organisms Intercalation with ergosterol → formation of pore complexes → depolarization → influx of H+ and efflux of K+ → lysis Oxidation of AmB by lipoxygenases → generate ROSs → membrane damage AZOLES ALL AZOLES ARE FUNGISTATIC RESISTANCE C. albican and C. krusei have intrinsic to fluconsazole Alteration in 14α-demethylase Increased ATP-binding cassette transporters MDR efflux Typically seen with prolonged therapy + treatment of oropharyngela candidiasis with fluconazole in AIDS patients AR Absolute Precautions Acute Infusion Toxicity Seen with high dose rates. Fever, chills, anorexia, nausea, myalgia, headache, vomiting. Delayed Nephrotoxicity Results in renal tubular injury, but typically does not lead to permanent renal isufficiency. Distal Tubular Acidosis Inhibits secretion of H+ into urine, resulting in Type I RTA. Normochromic Normocytic Anemia Suppresses EOI synthesis, but is readily reversible. Resistance Pharmacology Resistance is rare Typically solubilized in micellar formulations with deocycholate (a bile salt) for IV administration No dose adjustment in preexisting renal or hepatic failure Lipid formulations prevent oxidation to LDL:AmB, resulting in less renal tubular uptake and nephrotoxocity AmBisome AmB lipid complex AmB cooiloid dispersion Itraconazole Triazoles Bind and inhibit CYP450 14αDemethylase → inhibit transformation of lanosterol to ergosterol → increased 14αmethysterol:ergosterol → membrane disruption Fluconazole Spectrum Sporothrix schenkii, Aspergillus, Penicillium, Dermatiaceous fungi (phaeohyphomycetes) Sporotrichosis Limited Aspergillosis Endemic infections: Blastomycosis and Histoplasmosis Oral + esophageal candidiasis in AIDS patients, if resistant to fluconazole (C. glabrata, C. krusei) Spectrum Candida spp Albicans > parapsilosis> glabrata > krusei Dimorphic Systemic Fungi Ci > Hc > Bd Cryptococcus Neoformans Drug Interaction Via metabolism by CYP450. May increase bioavailability of codrug or decrease availability of azole Endocrine Effect Via occupation of normal CP450 involved in steroid synthesis Testosterone depletion → gynecomastia Glucocorticoid depletion → adrenal insufficiency Hepatotoxicity Limited CNS or ocular penetrance Good CNS and ocular penetrance NO ACTIVITY: Aspergillus and other hyphal pathogens Mucosal candidiasis Invasive candidemia Cryptococcal meningitis Endemic infections: Blastomycosis and Histoplasmosis DOC: coccidioidomycosis meningitis Spectrum EQUIVALENT to Fluconazole + Aspergillus + C. krusei, C. glabrata + T. biegillii + P. boydii (mycetoma) Voriconazole Good CNS and ocular penetrance DOC: aspergillosis DOC: most hyphal fungal infections ALLYLAMINES Terbinafine Bind to squalene epoxidase → depletion of lanosterol and egosterol → disruption of cell membrane → lysis Fungicidal Activity Spectrum Dermatophytes, Apsergillus, Dimorphics, Pneumocystis Very low Vd due to portien binding (non-saturable) Concentrated in the stratum corneum Onychomycosis Cutenaous dermatophyte infections Requires prolonged therapy ECHINOCANDINS Capsofungin Inhibits β(1,3) glucan syntehtase → depletion of cell wall glucans → lysis Similar to PCNs Spectrum Fungicidal: Candida (including C. glabrata and C. krusei) Fungistatic: Aspegillus (inhibits apical growth of hyphae) IV formulation only NO ACTIVITY: Cryptococcus, systemic dimorphics DOC: invasive candidiasis Combined with voriconazole for invasive aspergillosis FLUOROPYRIMIDINES 5-Fluorocytosone (5-FC) Fungal cytosine permease → transport into cell → convert to 5-FU via cytosine deaminase in cytosol → phosphorylate to F-UTP → interfers with RNA synthesis AND Conversion to F-dUMP → inhibit thymidylate synthetase → inhibit DNA synthesis Fungistatic activity Spectrum Yeast forms > hyphae DOC: 5-FC + AmB for cryptococcal meningitis Monotherapy: Candida UTI Myelosuppression Mammalian cells lack cytosine deaminase, but 5-FC is converted to 5-FU by NF in the gut DRUGS used in the treatment of VIRAL INFECTIONS ANTIVIRAL AGENTS General Features CLINICAL USES Influenza A only: Amantadine and Rimantidine (not approved) Influenza A and B: Oseltamivir and Zanamivir (N inhibitors) HSV-1 and HSV-2 (susceptible): Acyclovir, Valacyclovir, Famcyclovir CMV: Ganciclovir, Valganciclovir Resistant HSV and CMV: Cidofivir HCV: IFN-α, Adefovir, Tenefovir HBV: Equivalent to HCV + Telbivudine Interference with other nucleoside and nucleotide analogs occurs in concurrent treatment of HIV and HBV Most anti-herpes drugs are nucleoside analogs Drug (Generic Name) Amantadine Rimantidine Oseltamivir Zanamivir Acyclovir Famciclovir Class, Mechanism Receptor Activity Anti-Influenza Tricyclic Amine Actions and Therapeutic Uses Influenza A serotype only AR Absolute Precautions CNS effects: excitability Rimantadine does not cross BBB. Block M2 protein channel and prevent uncoating Blocks influx of protons from endosome into viral capsid Anti-Influenza Sialic acid analog Competes with N for cellular sialyl groups → no cleavage of virus during budding (remains bound to H) G Nucleoside Analog Resistance, Metabolism, other Remarks Res: point mutations in transmembrane domain of M2 Cross-resistance Influenza A and B NV Res: mutations in N HSV-1 > HSV-2 VZV NVD Headache Transient renal dysfunction Res: mutations or deficiency in TK Valacyclovir No activity: CMV (does not encode the TK) Phosphorylated by viral TK → additional phosphorylation cellular kinases → active triphosphate form Mutations in viral DNA Pol (these are not common) Termination of chain synthesis (no free 3’ OH) Inhibition of viral DNA Polymerase Ganciclovir Valganciclovir G Nucleoside Analog CMV HSV, VZV Severe neutropenia Res: mutations in UL97 kinase HSV and CMV if RESISTANT TO Acyclovir and Ganciclovir Renal toxicity Leukopenia No cross resistance HBV HCV Broad viral activity Fever, lethargy Myelosuppression Hypersensitivity CHF Res: seen in HCV Due to inhibition of PKR Phosphorylated by CMV UL97 kinase or HSV TK → additional phosphorylation by cellular kinases → active triphosphate form Termination of chain synthesis Inhibition of viral DNA Polymerase Cidofovir C Nucleotide analog Activation to triphosphate form by cellular kinases only : does not require viral activation Interferon-α Competes with dCTP → Inhibition of viral DNA polymerase Recombinant cytokine Increases expression of 2’-5’ oligoadenylate synthase Adefovir Tenefovir PKR RNAase L AMP Nucleotide Analog (Acyclic nucleoside phosphonates) Hepatic failure Pulmonary fibrosis HBV HCV Phsophorylation via cellular kinases → active diphosphate form Chain termination Inhibit DNA polymerase Telbivudine T Nucleoside Analog HBV only Does not inhibit human cellular polymerase RSV in peds with severe respiratory distress Broad spectrum DNA + RNA viral activity Transient hemolytic anemia Inhibits HBV RT (also a DNA polymerase) Does not require phosphorylation Ribavarin G Nucleoside Analog Active as triphosphate Inhibits IMP DH → decrease GMP Interferes with early replication (5’ mRNA capping) via depletion of GTP pools Direct inhibition of HCV RNA polymerase Combination with IFN-α: HCV HCV has RNA-dependent RNA polymerase ANTIRETROVIRAL AGENTS Enfuviritide Viral Fusion Inhibitor Salvage therapy if infection is refractory to multiple drugs Must be given by subcutaneous injection → results in injection site reactions Res: mutation of env region encoding GP41 R5 HIV infection AR: WNV infection due to CCR5 blockade Must determine viral tropism Conserved 36-residue peptide sequence from GP41 (HR2 domain) Maraviroc Inhibits folding of HR1 and HR2 → results in loss of conformational change upon binding of GP120 with CD4 Viral Entry Inhibitor Inhibits binding of GP120 with CCR5 co-receptor (R5 tropic strains) This is the main viral type in early infection, with conversion to X4 Zidovudine (AZT) Lamivudine (3TC) Stavudine (D4T) Abacivir Various nucleoside analogues Nucleoside RT Inhibitor NRTIs Phosphorylated by host cytoplasmic enzymes or HIV-1 TK Phosphorylation state determines absorbance Incorporation into strand duplex → chain termination Inhibits HIV-1 RT (p66 domain) Res: mutations in GP120 restoring ability to bindto CCR5 Main mechanism: development of mixed tropism Lactic Acidosis Inhibit mitochondrial DNA Pol-γ: cessation of mitochondrial DNA replication → increased lactate and TGs Hepatic Steatosis Presentation: NV, abdominal pain, dyspnea, AGMA, pancreatitis Hypersensitivity Myelosuppression Peripheral Neuropathy Res Mutations in RT nuceleotide-binding domain: decreased affinity for NRTIs Mutations in RT nuclease domain: increased hydrolysis of terminal NRTI from the leading strand (TAMs) (Increased affinity for dNTPs) Results in extensive cross-resistance Nevirapine Etravirine Delaviridine Efavirenz Various non-nucleoside structures Non-Nucleoside RT Inhibitor NNRTIs Rash Hepatotoxicity Efavirenz: CNS effects, teratogenicity Drug interactions: CYP3A4 metabolism Non-competitive irreversible inhibitors of RT If resistant to single firstgeneration drug, crossresistance is expected (use Efavirenz) Bind allosterically near the active site → conformational shift of catalytic Aspartate residues May potentiate effects of NTRIs Mutation → decreased 3’ hydrolytic activity → increased NTRI incorporation Does NOT require phosphorlyation Indanivir Saquinavir Atazanavir Ritonavir Lopinavir Protease Inhibitors Binds to the protease active site → prevents cleavage of Gag-Pol polyprotein Zidovudine antagonizes Stavudine due to competition for TK site Res Mutations in the NNTRI binding site → extensive cross-resistance Typically arises early with NNTRI monotherapy Lopinavir is coformulated with ritonivir (inhibits CP450 and increased bioavailability Hepatotoxicity GI distress Adipose redistribution Hyperlipidemia Insulin resistance ALSO potentiated by resistance mutations to NTRIs Res: mutations within protease binding site Drug class most likely to result in metabolic dysfunction Raltegravir Integrase Inhibitor Binds to the active site of HIV integrase and interferes with strand transfer Mutations in integrase DRUGS used in perioperative course of SOLID ORGAN TRANSPLANTATION GLOBAL IMMUNOSUPPRESSION Drug (Generic Name) Prednisone Class, Mechanism Activity Glucocorticoid Actions and Therapeutic Uses Blocks MHC II expression on APCs Decreases synthesis and secretion of cytokines (primarily from monocytes and macrophages) Blocks adhesion and extravasation of leukocytes Decreased synthesis of acute phase reactants High dose: direct lysis of lymphocytes Low-Dose: maintenance therapy High-Dose: acute rejection crisis Autoimmune diseases (hemolytic anemia, RA, SLE) ALL CLL AR Absolute Precautions Growth inhibition Protein catabolism and muscle wasting Adipose redistribution Suppression of the hypothalamicpituitary-adrenal axis Salt retention Cataracts Hyperglycemia Osteoporosis Psychosis Pharmacology A prodrug: must be metabolized to 11β-OH derivative for activity CALCINEURIN INHIBITORS Cyclosporine (CsA) Tacrolimus (FK506) Calcineurin Inhibitor Enters cell → binds cyclophilin (CsA) or immunophilin FK506 (Tactolimus) → complex with calmodulin and Ca2+ → cyclophilin:CsA and FK506:Tacrolimus inhibit the phosphatase activity of calcineurin → no dephosphorylation of NF-AT → remains inactive → no transcription of IL-2 Standard for primary immunosuppression Solid organ transplants (with other ISDs) Nephrotoxicity Neurotoxicity (tremor, headache, motor dysfunction, seizures) Hypertension Hyperglycemia, Hyperlipidemia Highly diabetogenic with prednisone Very narrow therapeutic window (plasma levels 150 – 200 ng/mL) Limiting factor is nephrotoxicity, although the drug is eliminated in the bile Metabolized by CYP3A4 Vastly increased potency (100X) compared to CsA Liver transplantation Rescue of acute kidney allograft rejection (refractory to cyclosporine) Mainly bound in plasma by albumin and α1glycoprotien Metabolized by CYP3A4 ANTI-METABOLITES Azothioprine Mycophenylate Mofetil Rapamycin (Sirolimus) Purine Synthesis Inhibitor Renal Transplants A complex mechanism of action Azothioprine → [glutathione and other SH groups] → 6mercaptopurine → [HGPRT] → 6-mercaptopurine ribose phosphate (6-thionosinic acid) → inhibit de novo synthesis of purines → conversion to 6thio-GMP and 6-thio-dGTP → inhibit DNA and RNA synthesis → global inhibition of cell proliferation Purine Synthesis Inhibitor No effect for ongoing chronic graft rejection! MMF → hydrolysis in GI tract → mycophenolic acid (MPA) → reversible non-competitive inhibition of inosone monophosphate dehydrogenase (IMP-DH) → cessation of de novo purine biosynthesis G1:S Transition Blockage Similar structure to FK506 (Tacrolimus) → complexes with FKBP → bind to mTOR → inhibition of G1:S transition → no proliferation in the presence of cytokines Highly selective to lymphocyte isoforms of IMP-DH (Type II) due to increased de novo purine synthesis Other cells use base salvage pathways Cytostatic effect on lymphocytes Inhibit glycosylation and expression of adhesions via depletion of guanosine nucleotides (decreased recruitment and inflammation) Prophylaxis of transplant rejection Used in combination with prednisone and calcineurin inhibitors Prophylaxis of transplant rejection Used in combination with prednisone and calcineurin inhibitors Use with predisone and MMF to avoid nephrotoxocity (main toxicity of calcineurin inhibitors) Use this to replace CsA and Tacrolimus Widespread ARs: Myelosuppression (leukopenia, anemia, thrombocytopenia) GI tract toxicity Hepatotoxicity Rashes Renal excretion Decreased toxicity compared to Azothioprine Renal excretion Myelosuppression (attenuated) GI tract toxicity Myelosuppression (anemia, leukopenia, thrombocytopenia) Hepatotoxicity GI tract toxicity Metabolized by CYP3A4 and eliminated in the bile ANTIBODIES ATG + ALG (antithymocyte and antilymphocyte globulins) OKT3 Polyclonal anti-T cell antibodies The immunoglobulins are generated by immunizing animal models with thymocytes and whole lymphocytes Monoclonal anti-T-cell antibody ATG and ALG bind non-specifically to T-cell surface antigens Blockade of TCR transduction Opsonophagocytosis in the RES Destruction by complement Rapid lymphocytopenia Chills Fever Leukopenia Thrombocytopenia Acute allograft rejection (only with other ISDs) Binds specifically to the CD3 protein (TCR subunit) Disruption of TCR-MHC recognition Opsonophagocytosis in the RES Destruction by complement Circulating T lymphocytes are depleted immediately after infusion. Acute allograft rejection (kidney, liver, heart) Rejection refractory to GC therapy Depletion of T cells from donor bone marrow (prep for transplantation) Cytokine Release Syndrome : highgrade fever, chills, NVD, myalgia, arthralgia, shock Premedicate with prednisone and/or NSAIDs Antibody response to exogenous Abs prevents repeated administration. DRUGS used in the treatment of HEMATOLOGIC DISORDERS HEMATOPOETIC DISORDERS Drug (Generic Name) Class, Mechanism Receptor Activity Actions and Therapeutic Uses Iron deficiency anemia Iron AR Absolute Precautions AR: GI effects (constipation, abdominal pain, dyspepsia), discoloration of teeth CI: hemochromatosis (Tx with deferoxamine) Megalobastic anemia due to B12 deficiency Cyanocobalamin (B12) Typically non-toxic CI: hereditary optic nerve atrophy (Leber’s disease) Megaloblastic anemia Supplementation to prevent neural tube defects Folic Acid (B9) Typically non-toxic AR: CNS effects (irritability, depression) with prolonged therapy Clearance, Metabolism, other Remarks Various iron salts contain different doses Parenteral: iron dextran Post-gastrectomy, duodenal reseaction, IBD, shortbowel syndrome Reticulocytosis within 2 -3 d. Typically, empiric treatment with B12 + folate is intiated until definitive Dx Inhibition of absorption Phenytoin, OCs, INH Inhibition of DHF Reductase Methotrexate, TMP, Pyrimethamine Erythropoetin Filgrastim Glycoprotein Action on EPO receptors expressed by erythoid progenitor cells Granulocytin colonystimulating fator (G-CSF) Tx low EPO anemia due to CKD Anemia in myelosuppression (secondary to ISD) Bone marrow transplantation Anemia of inflammation Increased neutrophils count without affect on other granulocytes AR: headache, seizures, HTN, edema, NVD, infusion toxicity (flu-like syndrome), hypokalemia (due to rapid erythropoeisis) CI: uncontrolled HTN, hypersensitivity to albumin AR: medullary bone pain, anaphylaxis Oprelvakin Recombinant IL-11 Tx neutropenia in myelosuppression (ISD), bone marrow transplant, aplastic anemia With chronic neutropenia, may be used to harvest peripheral progenitor cells Provokes growth of myeloid and lymphoid cell lines Accelerates megakaryocyte differentiation Prophylaxis of thrombocytopenia secondary to chemotherapy AR: edema, increased ECF results in hemodilution, transient loss of visual acuity, atrial arrhythmia, myelofibrosis Renal elimination May develop isoAbs, since Oprelvakin is structurally similar to native thrombopoeitin Romiplostim Second-generation thrombopoeitic agent Agonist at the TPO receptor Tx thrombocytopenia in chronic immune thrombocytopenic purpura (ITP) Must be enrolled in institutional network CI: renal failure and ESRD (relative) AR: CNS effects, myalgia, myelofibrosis No development of autoAbs ANTICOAGULANTS General Features These are used typically for venous thromboembolism (VTE) since clotting in the venous circulation preferentially involves the coagulation cascade Enoxaprin is DOC for Acute anticoagulation of DVT and pulmonary embolism Anticoagulation during pregnancy Post-op prophylaxis of DVT Lepirudin and argatroban (small-molecule inhibitor) are DOC for Anticoagulation in patients developing HIT (usually for post-op DVT prophylaxis) Bivalirudin is DOC for Prophylaxis of re-occlusion after coronary angioplasty in patients with HIT Warfarin is DOC for Long-term anticoagulation therapy, following short-course heparin, for prevention of VTE recurrence Atrial fibrillation and intracardiac thrombosis Unfractionated Heparin (UFH) 5 – 30 kD > 18 saccharides UFH → bind antithrombin III → stabilize antithrombin-III:thrombin complex → rapid inhibition of thrombin ALSO Binding of UFH → conformational change in AR: bleeding, HIT, osteoporosis, hypersensitivity Low bioavailability due to binding to plasma proteins Toxicity can be reversed via protamine sulfate Hepatic and renal elimination antithrombin III → increase affinity for Xa → increased inhibition of Xa 2 – 10 kD < 18 saccharides Low Molecular Weight Heparin (LMWH, Enoxaprin) BUT > 25% of molecules can inhibit thrombin Fondiparinux Lepirudin Argatroban Dabigatran Bivilarudin Warfarin Analogue of minor chain of heparin Direct Thrombin Inhibitor Small Molecule Direct Thrombin Inhibitors Inhibits thrombin and Xa LMWH → bind antithrombin III → conformational change → increased binding and inhibition of Xa AR: bleeding, HIT, osteoporosis, hypersensitivity Increased bioavailability Renal elimination NO binding to thrombin Predominantly inhibits Xa High molecular weight heparin chains may inhibit thrombin Decreased risk of bleeding relative to UFH Toxicity is not readily reversed by protamine sulfate DOC: DVT, Pulmonary Embolism DOC: anticoagulation during pregnancy Prophylaxis of VTE CI: renal insufficiency Inhibition of Xa only (similar to Enoxaprin) CI: renal insufficiency Similar efficacy to Enoxaprin for DVT Smaller molecule → direct inhibition of thrombin in clots Favors fibrinolysis Inhibits platelet aggregation (via decreasing action of thrombin) Longer half-life since it is not transformed AR: bleeding, hypersensitivity DOC: anticoagulation with HIT Used as an alternative to heparin (e.g. with HIT) Dabigatran: oral prodrug Inhibit circulating and bound thrombin Increased fibrinolysis Thus, used as adjuvants in thrombolytic therapy Factor Modification Inhibitor Prevents reduction of Vit K (compentive inhibitor) → inhibits γ-carboxylation of Gla domains on VitKdependent factors AR: bleeding, fetal hemorrhage (crosses placenta), warfarin-induced skin necrosis (due to coagulation) DOC: prophylaxis or recurrent VTE Requires therapy for 3 – 6 mos. Interactions Inhibit metabolism: phenytoin, Typically initiated with heparin to prevent coagulation DOC: atrial fibrillation metronidazole, cimetidine, acute EtOH Displace from albumin: aspirin Potentiate via anti-platelet effects: aspirin, phenylbutazone Decrease VitK: ABx Accelerate metabolism: barbiturates, rifampin, chronic EtOH ANTI-PLATLET DRUGS General Features These are typically used for arterial thromboembolism and thrombitc events secondary to atherosclerosis Aspirin is DOC for Unstable angina (Nitrates are used for stable angina) Prevention of thrombosis post-CABG Coronary angioplasty (combination with dipyrimdamole) Prevention of thrombosis with AV fistulae and valve prostheses Clopidogrel is DOC for TIA and ischemic stroke (note that prasugrel is actually contraindicated!) Abciximab, Eptifibatide, and Tirofiban are adjunct therapies in all PCI Aspirin Clopidogrel Prasugrel NSAID ADP receptor antagonist ADP receptor antagonist Irreversible inhibition of COX-1 in platelets and endothelium DOC: unstable angina Prophylaxis of thrombosis post-CABG Prophylaxis of thrombosis in stented coronary artery Acute MI TIA Irreversible blockage of ADP receptor (purinergic) → decreased platelet aggregation TIA Ischemic stroke Irreversible blockage of ADP receptor (purinergic) → decreased platelet aggregation AR: bleeding, increased risk of hemorrhagic stroke, GI bleeding, gastritis, hypersensitivity AR: immune-mediated thrombocytopenia and neutropenia, hemorrhage, drug interactions via CYP450 inhibition Ci: Hx of stroke of TIA Low-dose: inhibit platelet COX-1 without decreases PGI2 synthesis by endothelium Percutaneous coronary interventions (PCI): angioplasty, atherectomy, stenting Dipyridamole Phosphodiesterase Inhibitor Inhibit platelet PDE → increase intracellular cAMP → increase secretion of serotonin, ADP, ad TXA2 AR: headache, dizziness, flushing, nausea, diarrhea Aggrenox: dipyridamole + ASA Adjuvant with anticoagulants in patients with valve prosthesis Abciximab Eptifibatide Tirofiban GpIIb/IIIa antagonist RGD mimetic and GpIIb/IIIa antagonist Inhibits platelet aggregation (binding to fibrinogen and vWF) Adjunct therapy in PCI Refractory unstable angina Non-STEMI Competitive inhibitor of GpIIb/IIIa at the fibrinogen binding domain → inhibits aggregation AR: bleeding, thrombocytopenia AR: bleeding Adjunct therapy in PCI Unstable angina Non-STEMI FIBRINOLYTICS General Features DOC for thrombosis with imminent risk of vascular occlusion Ischemic stroke Acute STEMI Typically co-infused with antiplatelet and anticoagulant drugs to prevent rebound thrombosis at original clot site (due to excess liberated thrombin) Cleaves plasminogen to plasmin → fibronolysis AR: bleeding Tissue Plasminogen Serine protease Specific action on bound thrombin (this is still a significant side effect Activator despite limited activation of (Alteplase) DOC circulating thrombin) Acute MI Restoration of flow through occluded coronary artery Acute ischemic stroke DVT, pulmonary embolism, peripheral arterial Requires continuous infusion due to extremely short half-life thrombosis Urokinase Protease Cleaves plasminogen to plasmin → fibronolysis Does not require binding of thrombin to fibrin AR: bleeding, arrhythmia (due to clot lysis) HEMOSTATIC DRUGS General Features DDAVP can be used in most diseases causing thrombocytopenia or platelet dysfunction (e.g. vWD and uremia) Desmopressin (DDAVP) Aminocaproic Acid Thrombopoetin (Romiplistim, Eltrombopag) Recombinant VIIa Vit K Vasopressin analogue Anti-fibrinolytic TPO analogue Recombinant coagulation factor Increases secretion of vWF from endothelium DOC vWD Limited hemophilia A and B Thrombocytopenia Binds to plasminogen → inhibits cleavage and activation DOC Post-operative bleeding Intraoperative for CABG to minimize blood loss Thrombocytopenia TPO receptor agonists Triggers proliferation and differentiation of megakaryocytes DOC ITP DOC Hemostatis in patients with hemophilia and circulating inhibitors to replacement factors Uncontrolled hemorrhage Intracranial hemorrhage DOC Acute increase in INR with Warfarin therapy Pre-operative therapy if increased INR AR: water retention in collecting duct, hyponatremia, headaches, nausea, seizures AR: NVD, abdominal pain, thrombosis IV Renal excretion AR: thrombosis, rebound thrombocytopenia with abrupt discontinuation Subcutaneous IV Typically low-dose therapy due to risk of Warfarin resistance DRUGS used in the treatment of NEUROLOGICAL DISORDERS PARKINSON’S DISEASE Drug (Generic Name) Class, Mechanism Receptor Activity Actions and Therapeutic Uses AR Absolute Precautions Clearance, Metabolism, other Remarks Levodopa:Carbidopa Dopamine precursor + DOPA decarboxylase inhibitor Increases synthesis of DA (via DOPA-β-hydroxylase) Highly effective with gradual development of tolerance due to progressive loss of dopaminergic neurons 2 – 5 yr duration of effect Acute loss of efficacy End-interval tolerance (CNS concentration drops below therapeutic range) Shorted maintenance dose interval Entacapone or other metabolic inhibitor Dopamine agonist Abrupt “off” episodes May occur with high plasma levels; correlated with protein intake NV (activation of DA chemoreceptors in medulla) Dyskinesias CV: orthostatic hypotension, cardiac arrhythmias Psychosis (use atypical antipsychotics instead of DA antagonists) Discoloration of sweat and urine Reactivation of malignant melanoma Intake with food decreases absorption due to competition for enteric amino acid transporters Carbidopa does not cross BBB: no effect of L-DOPA conversion in CNS Carbidopa May reduce dosage of L-DOPA: decreased ARs Entacapone Tolcapone Reversible COMT inhibitor Used only with L-DOPA Inhibits peripheral conversion (GI and nerves) of L-DOPA to 3-O-MeDOPA Decreases conversion of L-DOPA into inactive metabolites: increased bioavailability and transport into CNS COMT inhibitor Tx PD if other drugs cannot be used Limit use to 3 wks if no response is observed May potentiate ARs of L-DOPA AR: hepatic failure Requires periodic LFTs CI: hepatitis, cirrhosis Selegiline Rasagiline Irreversible MAO-B inhibitor Adjunct to L-DOPA Prevents metabolism of DA in the CNS Tolerance develops within 2yrs May slow progression of PD Inhibits production of ROSs from crytic precursor toxin Similar efficacy to Selegiline AR: excitability Does not result in malignant hypertensive crisis due to selectivity for MAO-B Generalized flu syndrome, dyspepsia Metabolized by CYP 1A2 Pramipexole Dopamine receptor full agonist Selective binding to D2 and D3 Monotherapy for moderate PD Adjunct therapy (with L-DOPA) for advanced disease Selective binding to D2 and D3 Ropinirole Monotherapy for moderate PD Adjunct therapy (with L-DOPA) for advanced disease Bromocriptine Trihexyphenidyl D2 full agonist D1 partial agonist Monotherapy for moderate PD Adjunct therapy (with L-DOPA) for advanced disease Antimuscarinic agents Tx extrapyramidal symptoms (tremor, rigidity) without affect on bradykinesia Benztropine Renal excretion Combination Therapy AR: dyskinesias, hallucinations, orthostatic hypotension Less frequent than combination with Pramipexole Nausea Hallucinations, agitation, confusion Dyskinesias Orhtostatic hypotension Retroperitoneal and pulmonary fibrosis CI: elderly, abrupt discontinuation (may result in rebound tremors and parkinsonian symptoms) Hepatic elimination Use for young pts with moderate symptoms Diphenhydramine Amantadine Nausea, vertigo Dopamine reuptake inhibitor Stimulate DA release Muscarinic receptor antagonist NMDA receptor antagonist Second-line therapy CNS effects: confusion, anxiety Blurred vision, urine retention, xerostomia, constipation CI: combination with other antimuscarinic drug THE OPIOIDS General Features Receptors on the presynaptic terminal of the sensory afferent: µ, κ, δ Binding decreases Ca2+ influx →decreases transmitter release Receptors on the postsynaptic ascending (ALS) fiber: κ Binding increases K+ permeability Codeine and Hydrocodone: cannot be used for severe pain Meperidine: cannot be used for chronic therapy POTENCY Hydromorphone, Oxymorphone > Morphine, Oxycodone > Codeine, Hydrocodone Morphine Codeine Pure opioid receptor agonists Moderate to severe neuropathic and nociceptive pain May be used post-MI CNS effects Sedation, euphoria, anxiety, ‘clouded mentation’, dizziness, dyphoria Acute pulmonary edema Respiratory depression due to accommodation of central chemoreceptors to CO2 Depressed cough reflex Antitussive Antidiarrheal Anesthetics for cardiac surgery (Fentanyl) Hydromorphone Hydrocodone GI effects NV Simulation of medullary trigger Increased vestibular nuclear activity Diminishes with continued therapy Constipation Increased resting tone in GI smooth muscle Gastroparesis Biliary obstruction Oxycodone Oxymorphone Meperidine CV: Typically no clinical effects Some peripheral vasodilation: histamine release + depression of VM center Miosis Antidiuresis: increased secretion of Conjugated with glucuronic acid to M6G and M3G M66 has an extended half-life and higher receptor affinity M3G has toxic effects Converted to morphine by 0-demethylation Thus, it is a pro-drug Requires action of CYP2D6 This explains variability in response to codeine Less potent than morphine Dose ceiling Greater potency than morphine Only available in coformulation with NSAID Dose is limited by ASA and APAP toxicity! Equiavalent potency to morphine Greater potency than morphine Converted to mormeperidine by demethylation This is a toxic metabolite with excitatory effects Restrict use to short procedures ADH Methadone Used to Tx opioid dependence Pruritis and Urticaria Due to histamine release Tolerance Develops to analgesic effect Tolerance to GI pr papillary effects does not develop Propoxyphene Fentanyl Dependence Withdrawal syndrome (flu-like illness) Similar to mepiridine Converted to toxic metabolite Transdermal patch formulation Iontophoretic control system Trasnmucosal Addiction ARs can be minimized by opioid rotation and multi-drug therapy Buprenorphine Partial agonist Also considered a mixed agonist-antagonist Binds to the κ opioid receptor variant (presynaptic only) Analgesia (parenteral) Tx heroin addiction (sublingual) Low-dose: analgesic High-dose: antagonism and initiation of withdrawal syndrome May be less effective than methadone in long-term maintenance of opioid dependence Naloxone Pure opioid receptor antagonist Acts as antagonist at high doses Limited respiratory depression Refractory to reversal by naloxone due to slow receptor dissociation Decreased risk of abuse due to psychotropic effects Reversal of respiratory depression Heroin addiction Naltrexone Tramadol Can result in withdrawal syndrome if started on patient with chonic pure agonist Tx Binary analgesic Weak binding to µ receptors Inhibits reuptake of NE and Seizures Metabolite generate by Odemethylation → higher receptor affinity serotonin Dextromethorphan Opioid structural analog Cough suppression GENERAL ANESTHETICS General Features Complete anesthesia: hypnosis + amnesia + analgesia + relaxation Emergence: passive process dependent on clearance and re-distribution More rapid with volatile agents Slower with IV due to solubility Induction: typically achieved by IV Rapid-sequence: IV + intubation + neuromuscular block (succinylcholine) In peds: inhaled agents Maintenance: inhaled agents preferred (low tissue solubility and rapid respiratory elimination) DOC for induction without CV instability : Propofol, Thipental DOC for induction with CV instability : Etomidate (AR: apnea, adrenal suppression) DOC for induction in peds : Volatile agents DOC for maintenance : Volatile agents, Propofol Hypotension: Propofol > Thiopental Apnea : Etomidate, Propofol, Ketamine Increased CMRO2 : Ketamine Decreased CMRO2: Thiopental, Etomidate, Propofol, Volatile Agents Cerebral Vasodilation: Volatile Agents Thiopental GABA receptor agonist Potentiate binding of GABA on receptor IV induction Tx increased ICP Vasoconstricts the cerebral vessels and decreases oxygen demand At low concentration: hyperalgesic Venodilation Reflex tachycardia Respiratory depression (no apnea) Rapid onset and emergence IV induction in setting of cardiovascular dysfunction (e.g. hypotensive, CHF) Etomidate Neuroprotection Decreased CMRO2 and cerebral vasoconstriction Myoclonus Rapid onset and emergence NO cardiovascular effects Transient apnea Adrenal suppression IV induction Antiemetic Anesthetic maintenance (continuous infusion) Propofol Neuroprotection Signifacant CV effects (hypotension) Arteriolar and venous dilation Decreased SVR Decreased myocardial contractility (negative ionotrope) Rapid onset and emergence Transient apnea Ketamine Non-competitive NMDA receptor antagonist IV induction in setting of cardiovascular dysfunction Results in dissociative cataleptic anesthetic state Nystagmus with no consciousness Analgesia in burn dressings Significant analgesia Isoflurane Sevoflurane Desflurane Increased conductance of GABA ion channels Agonism of glycine receptors Blockade of T-type Ca2+ channels Inactivation of fast Na2+ Induction in peds Maintenance (preferred agents) Tx status asthmaticus status epilepticus (use volatile agents, not NO2) Neuroprotection Increased ICP Increased cerebral oxygen demand Emergence delirium Rapid onset and emergence Increased sympathetic outflow Increased myocardial oxygen demand Bronchodilation Increased respiratory secretion NO respiratory depression Cerebral vasodilation (increased ICP) Decreased cerebral oxygen demand Stable BP with increased CO Decreased SVR Decreased cardiac contractility Kinetics of onset and emergence: Determined by gas partition coefficient (solubility in plasma) channels No effect of APs Activation of tandem-pore K+ channels → hyperpolarization Nitrous Oxide NO2: Blockade of NMDA receptor Reflex tachycardia Respiratory depression Bronchodilation Mucociliary paralysis Airway irritation and bronchospasm Maintenance (preferred agents) Malignant hyperthermia: myolysis, hyperkalemia, hyperthermia, acidosis, renal failure, tetany Tx with dantrolene Inconsistent hypnosis and amnesia Must be given at 105% MAC (1.05 atm) for EC50 NO significant CV effects Increased PVR Expansion of pneumothorax or bowel lumen With chronic exposure Oxidation of cobalt complexed with B12 → homocysteinemia (atherosclerosis), sabacute comined degeneration (SCD) and neuroligc deficits , megaloblastic anemia LOCAL ANESTHETICS General Features STRUCTURE Hydrophobic pole with aromatic ring Hydrophilic pole (typically tertiary amine): required to bind to the Na+ channel from the cytoplasmic side Ester or Amide linkage Ester: degraded by plasma cholinesterases → amine + PABA (or derivative) PABA compounds may result in anaphylactoid reaction NO2 > Desflurane > Sevoflurane > Isoflurane Aminde: CYP1A2 and CYP3A4 N-de-alkylation, hydrolysis, hydroxylation CHEMISTRY Tertiary amines are weak bases: mainly protonated at pH 7.4 Lower pKa → faster onset due to ability to diffuse across membrane Increase rate of action: lower pKa, infusion with sodium bicarbonate Decrease rate of action: higher pKa, injection into inflamed and acidotic tissue KINETICS Fast onset: Cocaine, Benzocaine, Lidocain, Mepivicaine, Prilocaine Slow onset: Prociaine Open channel conformation → increased binding : use-dependent block MECHANISM Block fast Na+ channel ion pore from intracellular side Binds to Domain IV, α-helix S6 Must be reprotonated in the cytoplasm to have activity Binding → stabilize inactive state → prevent AP propagation At low concentrations : selectively blocks small axons (sensory) with sparing of motor function BLOCK TYPES Topical block: affects sensory nerve endings Subcutaneous infiltration (field block): minor procedures (IV insertion, suturing) Peripheral nerve block: anesthesia in territory of nerve Bier block (intravenous regional): exsanguinations of arm → occlude arterial flow → infusion of dilute lidocaine → reperfusion Neuraxial block: epidural and subarachnoid; results in anesthesia of all caudal spinal roots ABSORPTION Typically coformulated with epinephrine → local vasoconstriction at site of entry → local concentration and reduced systemic absorption Rate of absorption determine by regional perfusion: intercostals > epidural > brachial plexus > subcutaneous Bound by albumin and α1 acid glycoprotein GENERAL TOXICITY A farily stereotyped progression of symptoms CNS: sedation → excitation → circumoral paresthesias + tinnitus → NV, tremor, seizure → respiratory depression CLINICAL INDICATIONS Topical: cocaine, tetracaine (eye drops), benzocaine, prilocaine, lidocaine, EMLA Bolus Spinal Blocks: procaine, lidocaine (intraoperative), Continuous Spinal Block: bepuvicaine, ropivacaine Subcutaneous Infiltration: lidocaine, mepivacaine, bepuvacaine, ropivacaine Peripheral Nerve Block: same as SC IV cardioversion and anesthesia: lidocaine Beir Block: lidocaine LOCAL TOXICITIES Methemoglobinemia: benzocaine, prilocaine Occurs in presence of oxidative drugs Neurotoxicity (Cauda Equina Syndrome, Transient Radicular Irritation): lidocaine Cardiac toxicity (arrhythmias): bepuvacaine Ester-linked agent Topical: oral, nasal, pharyngeal mucosa Cocaine Vasoconstriction to confine other drugs (intraoperative) Spinal block (short duration) Procaine Eye drops: corneal and conjunctival anesthesia Spinal block Topical only on mucosa Ear drops Tetracaine Benzocaine Motor > sensory blockade Methemoglobinemia Oxidizes heme iron Results in hypoxemia Symptomatic with metHb > 35% Typically occurs in presence of mutiple oxidative drugs (e.g. sulfonamides, nitrates) Reverse with methylene blue (reduces metHb) Onset is slow since Benzocaine and Prilocaine are only used topically Lidocaine Amide-linked agent Suppress ventricular tachycardia Adjunct to general anesthesia Transdermal patch Neurotoxicity with intrathecal blocks: Cauda Equina Syndrome Transient radicular irritaition SC Block PN Block Beir Block Intraoperative neuraxial block SC Block PN Block Mepivacine SC Block PN Block Continuous epidural block (chronic pain) SC Block PN Block Continuous epidural block (chronic pain) Topical in coformulation with lidocaine (EMLA) Bupivacaine Ropivacaine Prilocaine EMLA Eutectic Mixture of Local Anesthetics Topical cream Transdermal patch 2.5% Prilocaine + 2.5% lidocaine Lowered melting point → increased absorption Severe cardiac toxicity Results in terminal ventricular arrhythmias Methemoglobinemia SEDATIVE and HYPNOTIC DRUGS Lorazepam Benzodiazepines Diazepam Bind to allosteric site on GABA(A) receptors and potentiate Cl- conductance with GABA binding Oxazepam Alprazolam Clonazepam DO NOT prolong the open state of the channel This is the mechanism of barbiturates Require γ subunit in GABA receptor for BZ binding AND α2 subunit for anxiolytic effect DOC: Acute attacks with GAD Panic disorders Sedation prior to invasive procedures Tx transient anxiety with initiation of antidepressant therapy May be used for insomnia Adjuncts for Tx of epilepsy IV diazepam for termination of status epilepticus Tx alcohol withdrawal Tapered dose regimine Daytime sedation Ataxia Memory dysfunction Paradoxical hostility and rage Fatal interaction with EtOH Teratogenicity (Risk D) Tolerance Develops to sedative effect NOT developed to anxiolytic effect Dependence Withdrawal symptoms (anxiety, anorexia, seizures) Addiction Immediate onset Extensive binding to plasma albumin Metabolism: hepatic conjugation and renal elimination De-alkylated metabolites have longer half-lives IF NOT HYDROXYLATED DOE NOT require the α1 subunit Flumezenil Zolpidem Zaleplon Eszoplicopne Ramelteon GABA receptor antagonist Non-benzodiazapine Receptor Agonists NBRAs PHYSIOLOGIC EFFECTS Sedation Hypnosis Amneisa Anyiolytic activity Muscle relaxation Anticonvulsant Reverse effects of Bz Overdose Post-interventional Hypnosis May be used to treat chronic insomnia Bind to distinct site on GABA receptor from Bz Require the α1 subunit Require γ subunit for binding Melatonin receptor agonist This is RARE, and is highly associated with history of substance abuse (in particular, EtOH). May result in panic attacks and convulsion if pt is dependent Interactions with EtOH: motor impairment, respiratory depression Hepatic metabolism and renal elimination Tolerance and Dependence Less than with Bz No active metabolites! Tx: Onset insomnia Buspirone Partial agonist of serotonin (5HT 1A) receptors GAD SSRIs (general) Inhibit serotonin reuptake by presynaptic neuron DOC for GAD and other anxiety disorders Not a ‘controlled substance’ No sedation No anticonvulsant or relaxant activity No EtOH interaction No dependence or addition Serotonin Syndrome Initial provocation of anxiety GI: ND SSRI withdrawal syndrome: flu-like symptoms Occurs with abrupt discontinuation Serotonin Syndrome Altered mental status, hypertonicity, autonomic Slow onset (2 – 4 wrks) Slow onset (2 – 6 wrks) dysfunction Occur with SSRI is combined with MAO inhibitor (inhibits metabolism) ANTIEPILEPTIC DRUGS General Features CLINICAL USES Primary Tonic-Clonic: phenytoin, valproate, carbamezapine Partial with Secondary Generalization: phenytoin, Lamotrigine, Oxcarbazepine (metabolite of carbamazepine) Absence: ethosuximide, valproate Atypical absence, Atonic: valproate Status Epilepticus: Lorezepam + Fosphenytoin GENERAL TOXICITIES CNS: sedation, dizziness, ataxia, blurred vision, some cognitive dysfunction Teratogenicity: associated mainly with the first-generation drugs Phenytoin First-Generation Agents Primary tonic-clonic Partial with secondary generalization Maintenance after termination of status epilepticus Gingival hypertrophy Hirsutism Hypersensitivty Osteomalacia + hypocalcemia Inhibits VitD absorption Folate deficiency VitK deficiency Valproic Acid Prolong Na+ Inactivation Phenytoin, carbamezapine, valporate Primary tonic-clonic Absence seizure Myoclonus, atonic seizure, atypical absence Teratogenicity Blood dyscrasias: aplastic anemia, neutropenia, thrombocytopenia Weight gain GI distress Tremor Decrease T-type Ca2+ conductance Ethosuximide, valproate Spina Bifida Partial with secondary generalization Primary tonic-clonic Blood dyscrasias: aplastic anemia, neutropenia, thrombocytopenia Phenobarbital Maintenance after termination of status epilepticus Teratogenicity Teratogenicity Ethosuxamide Absence seizure Involves abnormalities in T-type Ca2+ conductance Carbamezapine Potentiate GABA inhibition Clonazepam, diazepam, lorezepam, Phenobarbital Termination of status epileptics Must be followed by maintenance therapy (Fosphenytoin) Clonazepam Diazepam Lorazepam GABApentin Pregabelin Second-Generation Agents Typically used as second-line drugs for Tx of seizures Prolong Na+ Inactivation Lamotrigine, topiramate Pregabelin: fibromyalgia, neuropathic pain, GAD GABApentin: GAD Decrease Glutamate Release GABApentin, pregabelin Lamotrigine Topiramate Lamotrigine is a DOC for Partial and Secondarily Generalized seizures Bind to presynaptic α2δ domain of voltage-dependent Ca2+ channel → decreased secretion of excitatory transmitters Drug interactions via occupation of CYP450 Decreases plasma halflife of other drugs (including itself) Teratogenicity Tolerance Dependence Do not undergo metabolism Withdrawal syndrome Circulate unbound to plasma proteins Renal elimination Rash Toxic Epidermal Necrolysis ANTIDEPRESSANTS General Features ALL increase synaptic concentrations of monoamines (5-HT, NE) Requires 2 – 6 wks of therapy for onset of effects Proposed Mechansim Increased synaptic NT → increased cAMP → activation of cAMP Response Element Binding Protein → upregulation of p11 → increased 5-HT1B expression and transport METABOLISM Converted to active metabolites by CYP450 → conjugated with glucuronate → demethylated to metabolite with longer half-life DOC for GAD: SSRIs + initial benzodiazapines + Buspirone DOC for neuropathic pain: venlafaxine, duloxetine are used for diabetic polyneuropthy ; duloxetine, milnicipran for other chronic neurapthic pain DOC for fibromyalgia: pregabelin, duloxetine, milnicipran DOC for insomnia : atypical antidepressant (trazadone) CI: Bipolar depressive episode (may actually provoke mania) TOXICITIES ALL: mania in BP II SSRIs: initial anxiety, GI distress, weight gain, serotonin syndrome, SSRI discontinuation syndrome, teratogenicity Tricyclics: overdose fatality, muscarinic block (urinary retention, confusion, loss of visual acuity, xerostomia), adrenergic block (arrhythmias), sedation MAOIs: hypertensive crisis, interaction with SNRIs (hypertension) and SSRIs (serotonin syndrome) Fluoxetine Sertraline Paroxetine SSRI Selectively inhibit the reuptake of 5-HT into presynaptic neuron terminals DOC for treatment of GAD, MDD, PTSD, Panic Disorder, Eating Disorders Escitalopram Initial anxiety Insomnia Tremor GI distress Weight gain Serotonin Syndrome Hypothermia, tetany, myoclonus, mental status changes, autonomic dysfunction Citalopram SSRI Discontinuation Syndrome Least likely with fluoxetine due to long half-life Venlafaxine Duloxetine SNRI Selectively inhibit the reuptake of 5-HT and NE into presynaptic neuron terminals BUT no other receptor cross- Second-line for treatment of MDD Fibromyalgia: duloxetine, milnicipran (also pregabelin) Diabetic Polyneuropathy: venlafaxine, duloxetine Teratogenicity GI distress Insomnia Agitation Nausea Sedation reactivity Xerostomia, Constipation Desvenlafaxine Milnacipran Phenelzine Tranylcypromine MAO Inhibitors Inhibit oxidation of monoamines Second-line for treatment of MDD Selegiline Headache Xerostomia Postural Hypotension Malignant Hypertensive Crisis Occurs with intake of tyramine (converted to tyrosine and shunted into the monamine synthesis pathway) Can only initiated > 2 wks after discontinuation of SSRIs May result in serotonin syndrome (> 5 wks for fluoxetine due to long half-life) Serotonin Syndrome With concurrent or recent SSRI therapy Bupropion Atypical Antidepressants Inhibit the reuptake of 5-HT and NE into presynaptic neuron terminals BUT Non-tricyclic structure Second-line for treatment of MDD Tricyclic Antidepressants Inhibit the reuptake of 5-HT and NE into presynaptic neuron terminals Second-line for treatment of MDD Trazodone: Insomnia Dizziness Xerostomia Sweating, tremor Aggrevated psychosis High-dose: seizures Mirtazapine Nefazodone Trazodone Amitriptyline Desipramine Impramine Nortriptyline Blockade of diverse receptors H1, α1, muscarinic Overdose Toxicity Shock, respiratory depression, agitation, delirium, hyperpyrexia, conduction block, arrhythmias Muscarinic Blockade Xerostomia, cycloplegia, urinary retention, confusion Amitritptyline → Nortriptyline Imapramine → Desipramine Adrenergic Blockade Orthostatic hypotension, QT prolongation, cardiac arrhythmias Histaminergic Agonism Sedation Amphetamines Hypericin DOC if MDD is refractory to standard therapy No FDA approval No demonstrated efficacy Increases CYP3A4 activity Thus, may result in significant drug interactions MOOD STABILIZERS : TREATMENT of BIPOLAR DISORDER General Features ACUTE MANIA Initiate with atypical antipsychotic Elaborate therapy with moos stabilizer (lithium, antiepileptic) when oral compliance is assured Lithium + Valproate + Atypical Antipsychotic (aripiprazole, olanzapine) BIPOLAR DEPRESSION Any antidepressant. SSRIs preferred. MAINTENANCE Lithium + Anti-Epileptic (valproate) DO NOT use antidepressant monotherapy TOXICITY Lithium: hypothyroidism, neurogenic myopathy, fine fremor, GI distress, nephrogenic DI, weight gain, arrhythmias, hypotension Acute intoxication, sever neurologic toxicity, drug interactions, teratogenicity Atypical Antipsychotics: DM II, weight gain, hyperprolactinemia, prolonged QT (adrenergic block), dyslipemia DOC: Bipolar Disorder (I and II) No psychotropic effects in NML Lithium Decreases expression of ANK3 subjects and CACNA1C Suppresses acute manic episodes ANK3: regulates formation Use in maintenance Thyromegaly and insertion of neuronal Use with advent antidepressant or antipsychotic for (indicates dysfunctional synthesis Na+ channels acute MDE of thyroxine) Acute Mania: 0.8 – 1.2 mEq/L Maintenance: 0.6 – 0.8 mEq/L Onset within 2 wks Not metabolized CACNA1C: subunit of neuronal calcium channel (Hypothyroidism) Some insulin-like effects Neurologic: muscle fatigue, lethargy, fine tremor WITH SEVERE NEUROTOXICITY Confusion, hyperreflexia, gross tremor, dysarthria, seizures, focal signs, CN deficits Increases monoamine metabolism (deamination) Suppresses DA receptor transduction Increases BCL-2 levels within neurons This is neuroprotective (aniapoptotic) GI: anorexia, NV Renal: Nephrogenic DI, RTA, albuminuria CV: cardiac arrhythmias, hypotension Drug Interactions: Thiazides, loop diuretics, NSAIDs, ARBs, ACE inhibitors Acute intoxication: vomiting, diarrhea, coarse tremor, ataxia, convulsions, coma Acute minor toxicity: GI distress, sedation, fine tremor Teratogenic: congenital cardiac defects Aripiprazole Olanzapine Quetiapine Atypical antipsychotic agents DOC as adjunct to Lithium in acute mania (with oral compliance) Renal elimination with 80% reabsorbed in the PCT Carbamezapine Lamotrigine Valproate DEMENTIA General Features Treatment recommendation: AchE inhibitor + VitE Only approved for patients with limited and moderate dementia These drugs delay progression of cognitive decline Improve QoL, cognitive function, agitation ELEMENTS in the PATHOGENESIS of AD Hippocampal →cortical degeneration of neurons ACh depletion Aβ: perivascular deposition and within neurotic plaques May be generated by mutations in APP (Ala692Gly and Val717X) → results in abnormal proteolysis and formation of Aβ42 Neurofibrillary tangles Abnormal tau and microtubule filaments ApoE4 → decreased plaque solubility ERAB Elevated plasma homocysteine May be reduced by B12, B6, and folate supplementation Glutamate Basis of therapy with memantidine AChE Donepezil AchE inhibitors Rivastigmine is a semiirreversible inhibitor (carboymylates the active site of AchE) DOC for cognitive sparing in AD Peripheral ARs due to excess cholinergic signaling: Nausea, diarrhea Bradycardia CI: GI bleeding Selective for CNS isoform of AChE Second-line in treatment of AD Rivastigmine Donepezil and Galantamine are reversible inhibitors CNS: dizziness, headache, sedation, tremor Prominent PNS cholinergic effects: NVD, abdominal pain, anorexia Weight loss Exacerbate peptic ulcer disease Bradycardia Urinary obstruction Bronchoconstriction Intake with meals (increases absorption) However, peak plasma concentrations are decreased CI: GI bleeding Second-line in treatment of AD Galantamine NVD, anorexia Weight loss Bronchoconstriction CI: GI bleeding, hepatic or renal impairment Memantine NMDA receptor antagonist May actually result in symptom improvement Decreases glutamate neurotransmission → protection of neurons from cytotoxic influx of Ca2+ CI: renal failure Allows appropriate influx with high synaptic concentrations of glutamate Thus, blocks the tonic pathological glutamate release ANTIPSYCHOTICS General Features PHARMACOLOGY Ramped dosing All drugs are highly lipid-soluble with large Vd Thus, plasma levels do not correlate with therapeutic effect or toxicity Parenteral depot forms: fluphenazine, haloperidol, resperidone Rapid IM form: ziprasidone METABOLISM Extensive transformation and slow elimination (may have slow reemergence of symptoms) Renal elimination of glucuronidated metabolite CLINICAL EFFECT Typical: reduce positive psychotic symptoms (delusions, hallucinations). No effect on negative symptoms. Atypical: recue positive and negative symptoms. May be used in Bipolar manic and depressive episodes. ADVERSE EFFECTS Typicals: higher incidence of EPS, hyperprolactinemia Atypical: weight gain, dyslipidemia, DMII Shared: autonomic effects Aripiprazole: partial agonist activity at D2 (thus, must be used at sufficiency high doses for antagonism) Clozapine, Olanzapine: avid anti-muscarinic activity, also most extreme weight gain Ziprasidone, Aripiprazole: least weight gain Chlorpromazine Typical Antipsychotics (‘Neuroleptics’) Fluphenazine Perphenazine Thiothixene Trifluoperazine Blockade of D2 > 5-HT2 receptors Therapeutic effect derived from DA antagonism in the mesocorticolimbic pathway! Haloperidol Clozapine Atypical Antipsychotics Olanzapine Blockade of 5-HT2 > D2 receptors (There is still significant Risperidone DOC for active and residual schizophrenia DOC for bipolar mania Adjuvant in bipolar MDE ARs mainly ASSOCIATED WITH TYPICALS High affinity for 5-HT2A Nigostriatal Blockade EPS: Parkinsonism, Acute Dystonia, Akatheisia, Neuroleptic Malignant Syndrome, Perioral Tremor, Tardive Duskinesia IM depot formulation: fluphenzine decanoate Tubuloinfundibular Blockade Hyperprolactinemia Females: Amenorrhea, galactoerhea, infertility Males: decreased libido, impotence, infertility This is seen with ALL typical drugs Also seen with atypical Respiridone IM depot formulation: haloperidol decanoate Must track CBCs weekly IM depot formulation Quetiapine Ziprazidone activity at D2) May be used in elderly patients with dementia and psychosis BUT increased mortality Aripiprazole Palperidone Prochlorperazine Tardive Dyskinesia (This is actually an EPS) Presents as oral and facial dyskinesia Dysphagia, chocking, dysarthria, dyspnea May also involve generalized dystonia or choreoathetosis Occurs with long-term therapy with typical antipsychotics Due to upregulated D2 receptors: increased sensitivity Thus, discontinuation of therapy may exacerbate symptoms Antiemetic only Jaundice and blood dyscrasias Toxic and Allergic Dermatitis ARs mainly ASSOCIATED with BOTH CLASSES Adrenergic Blockade Orthostatic hypotension, urinary retention, sexual dysfunction Muscarinic Blockade CNS: confusion, delirium Seen with clozapine, olanzapine H1 Blockade Results In sedation Seizures Agonist at 5-HT1A Rapid IM formulation Agonist at 5-HT1A Partial agonist at D2 Primary metabolite of resperidone This is a controlled release system Typicals: chlorpromazine Atypicals: clozepine Neuroleptic Malignant Syndrome Hyperthermia, hypertonia, stupor, fluctuating BP Distinguish from malignant hyperthermia No responsive to dantrolene Cardiac Toxicity Increased risk of ventricular arrhythmia due to prolonged QT interval Agranulocytosis: clozapine ARs ASSOCIATED WITH ATYPICALS Weight Gain Seen with olanzapine and clozapine Glucose Intolerance and Insulin Resistance Highest incidence with clozapine Hyperlipidemia Probably due to weight gain Increased mortality in elderly with psychotic dementia STIMULANTS General Features Only approved for TX of ADHD and narcolepsy These are distinct from antidepressants: cause generalized excitation due to effects on DA and NE Related to atypical (heterocyclic) antidepressants (e..g Bupropion) BUT not used to TX MDD Atomoxetine: NRI; nonstimulant Modafinil: non-amphetamine stimulant Actually inhibits neurons in the VLPO ; some action at DAT and NET Methyphenydate: equivalent to amphetamine Amphetamine stimulant TX: ADHD, narcolepsy Amphetamine Many ARs due to sympathetic stimulation S:R isomers in 3:1 formulation Inhibits NE, DA, and 5-HT reuptake AND Stimulates release of all monoamines Elevated mood Increase wakefulness Increase concentration Decreased fatigue Anorectic effect Potentiates analgesic effect of opioids CNS: insomnia, agitation, effusiveness, psychosis CV: arrhythmias, angina (increased myocardial contractility), HTN Metabolism via MAO and CYP Urinary elimination is sensitive to pH Weight loss Overdose Toxicity: confusion, psychosis, HTN, palpitations, convuslions Mortality due to cerebral Hemorrhage TX: phentolamine (adrenergic blocker; reduces BP), diazepam (control seizures), acidification of urine Withdrawal: avolution, abulia, depression CI: anxiety, anorexia nervosa, psychosis, CAD, HTN, arteriosclerosis, MAOIs, hyperthyroidism, glaucoma Atomoxetine Non-stimulant TX: ADHD only Selective NE reuptake inhibitor (NRI) No potential for abuse Typically no ARs at low doses May have increased risk of SI Cocaine Amphetamine stimulant Methamphetamine Amphetamine stimulant Topical formulation for local anesthesia Slow onset (1 – 3 wks) Modafinil Methylphenidate Non-amphetamine stimulant Used to increase wakefulness Acts on circadian structures of the hypothalamus Inhibits the VLPO (via blockade of NE reuptake) TX: narcolepsy, shift-work sleep disorder, and OSA Off-label: ADHD, depression, fatigue (occupational, chemotherapy), AD Binds to DA and NE reuptake transporters BUT action is not antagonized by haloperidol Stimulant Equivalent to amphetamine Headache Nausea Diarrhea Anxiety CI: peds, MAOIs, hepatic failure TX: ADHD, narcolepsy This is the most commonly used medication in pediatric ADHD Available in three different formulations with varying kinetics HALLUCINOGENS Lysergic Acid Diethylamide (LSD) Partial agonist at 5-HT Produces the psychedelic experience Activity at other monoamine receptors Physiologic effects: mydriasis, HTN, tachycardia, flushing, hyperreflexia (Requires ≤ 50 µg for effects) Tachyphylaxis: rapid tolerance Cross-tolerance with LSD, psilocybin, and mescaline NO physical dependence Psychosis Psilocybin Partial agonist at 5-HT2A Mescaline Activity at other monoamine receptors Found in peyote Partial agonist at 5-HT2A Activity at other monoamine receptors High potency Produces the psychedelic experience Virtually equivalent to LSD, but less potent Weak hallucinogen Used to normalize and quantitate psychedelic activity of other drugs Used in NAC and two native groups in Mexico NV Tolerance develops with repeated use MDMA This is actually a derivative of mescaline Entactogen ‘Ecstacy’ N-methyl derivative of MDA Produces a unique psychological state: Empathy, openness, acceptance Previously used in psychotherapy Neurotoxicity With repeated dosing: depletion of CNS serotonin Causes degeneration of serotonergic axon terminals May be prevented by pretreatment with SSRIs Blocks reuptake of 5-HT, DA, and NE Increases release of 5-HT, DA, NE Requires monoamine transporters to enter the neuron Direct agonism at 5-HT2A Marijuana Exogenous cannabanoid Bind to CNS CB1 and CB2 receptors Subjective effects: euphoria, sedation, visual and auditory hypersensitivity, tactile enhancement, increased appetite Impairment of STM Depersonalization Hallucinations, paranoia, anxiety TX: pain, antiemetic in pts undergoing chemotherapy CV: tachycardia, vasodilation (conjunctival eythema, orthostatic hypotension) Glaucoma (lowers IOP) Muscle spasms Insomnia Antipyretic May slow progression of AD: inhibits amyloid plaque formation Respiratory: bronchodilation (acute) and bronchoconstriction (chronic), lung carcinoma No physical dependence seen with moderate use