Cardiovascular - Pharmacology Flashcards
Antihypertensive therapy
- Primary (essential) hypertension
- Hypertension with CHF
- Hypertension with diabetes mellitus
- Primary (essential) hypertension
- Diuretics, ACE inhibitors, angiotensin II receptor blockers (ARBs), calcium channel blockers.
- Hypertension with CHF
- Diuretics, ACE inhibitors/ARBs, β-blockers (compensated CHF), aldosterone antagonists.
- β-blockers must be used cautiously in decompensated CHF and are contraindicated in cardiogenic shock.
- Hypertension with diabetes mellitus
- ACE inhibitors/ARBs, calcium channel blockers, diuretics, β-blockers, α-blockers.
- ACE inhibitors/ARBs are protective against diabetic nephropathy.
Calcium channel blockers
- Examples
- Mechanism
- Clinical use
- Toxicity
- Examples
- Amlodipine, nimodipine, nifedipine (dihydropyridine)
- Diltiazem, verapamil (non-dihydropyridine).
- Mechanism
- Block voltage-dependent L-type calcium channels of cardiac and smooth muscle, thereby reduce muscle contractility.
- Vascular smooth muscle
- Amlodipine = nifedipine > diltiazem > verapamil.
- Heart
- Verapamil > diltiazem > amlodipine = nifedipine
- Verapamil = ventricle
- Clinical use
- Dihydropyridine (except nimodipine): hypertension, angina (including Prinzmetal), Raynaud phenomenon.
- Non-dihydropyridine: hypertension, angina, atrial fibrillation/flutter.
- Nimodipine: subarachnoid hemorrhage (prevents cerebral vasospasm).
- Toxicity
- Cardiac depression, AV block, peripheral edema, flushing, dizziness, hyperprolactinemia, and constipation.
Hydralazine
- Mechanism
- Clinical use
- Toxicity
- Mechanism
- Increases cGMP –> smooth muscle relaxation.
- Vasodilates arterioles > veins
- Afterload reduction.
- Clinical use
- Severe hypertension, CHF.
- First-line therapy for hypertension in pregnancy, with methyldopa.
- Frequently coadministered with a β-blocker to prevent reflex tachycardia.
- Toxicity
- Compensatory tachycardia (contraindicated in angina/CAD), fluid retention, nausea, headache, angina, Lupus-like syndrome.
Hypertensive emergency
- Commonly used drugs
- Nitroprusside
- Fenoldopam
- Commonly used drugs
- Nitroprusside, nicardipine, clevidipine, labetalol, and fenoldopam.
- Nitroprusside
- Short acting
- Increases cGMP via direct release of NO.
- Can cause cyanide toxicity (releases cyanide).
- Fenoldopam
- Dopamine D1 receptor agonist—coronary, peripheral, renal, and splanchnic vasodilation.
- Decreases BP and increases natriuresis.
Nitroglycerin, isosorbide dinitrate
- Mechanism
- Clinical use
- Toxicity
- Mechanism
- Vasodilate by increasing NO in vascular smooth muscle –> increase in cGMP and smooth muscle relaxation.
- Dilate veins >> arteries.
- Decreases preload.
- Clinical use
- Angina, acute coronary syndrome, pulmonary edema.
- Toxicity
- Reflex tachycardia (treat with β-blockers), hypotension, flushing, headache
- “Monday disease” in industrial exposure: development of tolerance for the vasodilating action during the work week and loss of tolerance over the weekend results in tachycardia, dizziness, and headache upon reexposure.
Antianginal therapy
- Goal
- Calcium channel blockers
- Pindolol and acebutolol
- Nitrates
- β-blockers
- Goal
- Reduction of myocardial O2 consumption (MVO2) by decreasing 1 or more of the determinants of MVO2: end-diastolic volume, blood pressure, heart rate, contractility.
- Calcium channel blockers
- Nifedipine is similar to nitrates in effect
- Verapamil is similar to β-blockers in effect.
- Pindolol and acebutolol
- Partial β-agonists contraindicated in angina.
- Nitrates
- Affect preload.
- β-blockers
- Affect afterload.
Antianginal therapy
- For each: increased, decreased, or little/no effect
- Nitrates
- β-blockers
- Nitrates + β-blockers
- End-diastolic volume
- Blood pressure
- Contractility
- Heart rate
- Ejection time
- MVO2
- End-diastolic volume
- Nitrates: Decreased
- β-blockers: Increased
- Nitrates + β-blockers: No effect or decreased
- Blood pressure
- Nitrates: Decreased
- β-blockers: Decreased
- Nitrates + β-blockers: Decreased
- Contractility
- Nitrates: Increased (reflex response)
- β-blockers: Decreased
- Nitrates + β-blockers: Little/no effect
- Heart rate
- Nitrates: Increased (reflex response)
- β-blockers: Decreased
- Nitrates + β-blockers: Decreased
- Ejection time
- Nitrates: Decreased
- β-blockers: Increased
- Nitrates + β-blockers: Little/no effect
- MVO2
- Nitrates: Decreased
- β-blockers: Decreased
- Nitrates + β-blockers: Really decreased
Lipid-lowering agents:
HMG-CoA reductase inhibitors (lovastatin, pravastatin, simvastatin, atorvastatin, rosuvastatin)
- Effect on LDL
- Effect on HDL
- Effect on triglycerides
- Mechanisms of action
- Side effects / problems
- Effect on LDL (“bad cholesterol”)
- Really really decreased
- Effect on HDL (“good cholesterol”)
- Increased
- Effect on triglycerides
- Decreased
- Mechanisms of action
- Inhibit conversion of HMG-CoA to mevalonate, a cholesterol precursor
- Side effects / problems
- Hepatotoxicity (increased LFTs), rhabdomyolysis (esp. when used with fibrates and niacin)

Lipid-lowering agents:
Niacin (vitamin B3)
- Effect on LDL
- Effect on HDL
- Effect on triglycerides
- Mechanisms of action
- Side effects / problems
- Effect on LDL (“bad cholesterol”)
- Really decreased
- Effect on HDL (“good cholesterol”)
- Really increased
- Effect on triglycerides
- Decreased
- Mechanisms of action
- Inhibits lipolysis in adipose tissue
- Reduces hepatic VLDL synthesis
- Side effects / problems
- Red, flushed face, which is decreased by aspirin or long-term use
- Hyperglycemia (acanthosis nigricans)
- Hyperuricemia (exacerbates gout)

Lipid-lowering agents:
Bile acid resins (cholestyramine, colestipol, colesevelam)
- Effect on LDL
- Effect on HDL
- Effect on triglycerides
- Mechanisms of action
- Side effects / problems
- Effect on LDL (“bad cholesterol”)
- Really decreased
- Effect on HDL (“good cholesterol”)
- Slightly increased
- Effect on triglycerides
- Slightly increased
- Mechanisms of action
- Prevent intestinal reabsorption of bile acids
- Liver must use cholesterol to make more
- Side effects / problems
- Patients hate it—tastes bad and causes GI discomfort, decreased absorption of fat-soluble vitamins
- Cholesterol gallstones

Lipid-lowering agents:
Cholesterol absorption blockers (ezetimibe)
- Effect on LDL
- Effect on HDL
- Effect on triglycerides
- Mechanisms of action
- Side effects / problems
- Effect on LDL (“bad cholesterol”)
- Really decreased
- Effect on HDL (“good cholesterol”)
- No effect
- Effect on triglycerides
- No effect
- Mechanisms of action
- Prevent cholesterol absorption at small intestine brush border
- Side effects / problems
- Rare increased LFTs, diarrhea

Lipid-lowering agents:
Fibrates (gemfibrozil, clofibrate, bezafibrate, fenofibrate)
- Effect on LDL
- Effect on HDL
- Effect on triglycerides
- Mechanisms of action
- Side effects / problems
- Effect on LDL (“bad cholesterol”)
- Decreased
- Effect on HDL (“good cholesterol”)
- Increased
- Effect on triglycerides
- Really really decreased
- Mechanisms of action
- Upregulate LPL –> increased TG clearance
- Activates PPAR-α to induce HDL synthesis
- Side effects / problems
- Myositis (increased risk with concurrent statins), hepatotoxicity (increased LFTs), cholesterol gallstones (esp. with concurrent bile acid resins)

Cardiac glycosides
- Examples
- Mechanism
- Clinical use
- Toxicity
- Antidote
- Examples
- Digoxin
- 75% bioavailability
- 20–40% protein bound
- t1/2 = 40 hours
- Urinary excretion.
- Digoxin
- Mechanism
- Direct inhibition of Na+/K+ ATPase leads to indirect inhibition of Na+/Ca2+ exchanger/antiport.
- Increased [Ca2+]i –> positive inotropy.
- Stimulates vagus nerve –> decreased HR.
- Clinical use
- CHF (increased contractility)
- Atrial fibrillation (decreased conduction at AV node and depression of SA node).
- Toxicity
- Cholinergic—nausea, vomiting, diarrhea, blurry yellow vision (think Van Gogh).
- ECG—increased PR, decreased QT, ST scooping, T-wave inversion, arrhythmia, AV block.
- Can lead to hyperkalemia, which indicates poor prognosis.
- Factors predisposing to toxicity—renal failure (decreased excretion), hypokalemia (permissive for digoxin binding at K+-binding site on Na+/K+ ATPase), verapamil, amiodarone, quinidine (decreased digoxin clearance; displaces digoxin from tissue-binding sites).
- Antidote
- Slowly normalize K+, cardiac pacer, anti-digoxin Fab fragments, Mg2+.
Antiarrhythmics—Na+ channel blockers (class I)
- Slow or block (decrease) conduction (especially in depolarized cells).
- Decrease slope of phase 0 depolarization and increase threshold for firing in abnormal pacemaker cells.
- Are state dependent (selectively depress tissue that is frequently depolarized [e.g., tachycardia]).
- Hyperkalemia causes increased toxicity for all class I drugs.
Antiarrhythmics—Na+ channel blockers (class IA)
- Examples
- Mechanism
- Clinical use
- Toxicity
- Examples
- Quinidine, Procainamide, Disopyramide.
- “The Queen Proclaims Diso’s pyramid.”
- Mechanism
- Increased AP duration, increased effective refractory period (ERP), increased QT interval.
- Clinical use
- Both atrial and ventricular arrhythmias, especially re-entrant and ectopic SVT and VT.
- Toxicity
- Cinchonism (headache, tinnitus with quinidine), reversible SLE-like syndrome (procainamide), heart failure (disopyramide), thrombocytopenia, torsades de pointes due to increased QT interval.

Antiarrhythmics—Na+ channel blockers (class IB)
- Examples
- Mechanism
- Clinical use
- Toxicity
- Examples
- Lidocaine, Mexiletine.
- Mechanism
- Decrease AP duration.
- Preferentially affect ischemic or depolarized Purkinje and ventricular tissue.
- Phenytoin can also fall into the IB category.
- Clinical use
- Acute ventricular arrhythmias (especially post-MI), digitalis-induced arrhythmias.
- IB** is Best post-MI.**
- Toxicity
- CNS stimulation/depression, cardiovascular depression.

Antiarrhythmics—Na+ channel blockers (class IC)
- Examples
- Mechanism
- Clinical use
- Toxicity
- Examples
- Flecainide, Propafenone.
- “Can I have Fries, Please.”
- Mechanism
- Significantly prolongs refractory period in AV node.
- Minimal effect on AP duration.
- Clinical use
- SVTs, including atrial fibrillation.
- Only as a last resort in refractory VT.
- Toxicity
- Proarrhythmic, especially post-MI (contraindicated).
- IC** is Contraindicated in structural and ischemic heart disease.**

Antiarrhythmics—β-blockers (class II)
- Examples
- Mechanism
- Clinical use
- Toxicity
- Examples
- Metoprolol, propranolol, esmolol, atenolol, timolol, carvedilol.
- Mechanism
- Decrease SA and AV nodal activity by decreasing cAMP, decreasing Ca2+ currents.
- Suppress abnormal pacemakers by decreasing slope of phase 4.
- AV node particularly sensitive—increased PR interval.
- Esmolol very short acting.
- Clinical use
- SVT, slowing ventricular rate during atrial fibrillation and atrial flutter.
- Toxicity
- Impotence, exacerbation of COPD and asthma, cardiovascular effects (bradycardia, AV block, CHF), CNS effects (sedation, sleep alterations).
- May mask the signs of hypoglycemia.
- Metoprolol can cause dyslipidemia.
- Propranolol can exacerbate vasospasm in Prinzmetal angina.
- Contraindicated in cocaine users (risk of unopposed α-adrenergic receptor agonist activity).
- Treat overdose with glucagon.

Antiarrhythmics—K+ channel blockers (class III)
- Examples
- Mechanism
- Clinical use
- Toxicity
- Examples
- Amiodarone, Ibutilide, Dofetilide, Sotalol.
- “AIDS.”
- Mechanism
- Increase AP duration, increase ERP.
- Used when other antiarrhythmics fail.
- Increase QT interval.
- Clinical use
- Atrial fibrillation, atrial flutter
- Ventricular tachycardia (amiodarone, sotalol).
- Toxicity
- Sotalol—torsades de pointes, excessive β blockade.
- Ibutilide—torsades de pointes.
- Amiodarone—pulmonary fibrosis, hepatotoxicity, hypothyroidism/ hyperthyroidism (amiodarone is 40% iodine by weight), corneal deposits, skin deposits (blue/gray) resulting in photodermatitis, neurologic effects, constipation, cardiovascular effects (bradycardia, heart block, CHF).
- Remember to check PFTs, LFTs, and TFTs when using amiodarone.
- Amiodarone has class I, II, III, and IV effects and alters the lipid membrane.

Antiarrhythmics—Ca2+ channel blockers (class IV)
- Examples
- Mechanism
- Clinical use
- Toxicity
- Examples
- Verapamil, diltiazem.
- Mechanism
- Decrease conduction velocity, increase ERP, increase PR interval.
- Clinical use
- Prevention of nodal arrhythmias (e.g., SVT), rate control in atrial fibrillation.
- Toxicity
- Constipation, flushing, edema, CV effects (CHF, AV block, sinus node depression).

Other antiarrhythmics
- Adenosine
- Mg2+
- Adenosine
- Increasing K+ out of cells –> hyperpolarizing the cell and decreasing ICa.
- Drug of choice in diagnosing/abolishing supraventricular tachycardia.
- Very short acting (~ 15 sec).
- Adverse effects include flushing, hypotension, chest pain.
- Effects blocked by theophylline and caffeine.
- Mg2+
- Effective in torsades de pointes and digoxin toxicity.