Cardiovascular diseases remain one of the leading causes of morbidity worldwide. To combat angina, hypertension, and edema, modern therapeutics rely on a range of drug classes—each with distinct mechanisms and clinical applications. Unit 2 introduces students to anti-anginal agents, calcium channel blockers, diuretics, and antihypertensive drugs that form the backbone of cardiovascular pharmacotherapy. Understanding their pharmacological profiles equips future pharmacists with the knowledge required for optimal patient care.
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Anti-Anginal Drugs: Restoring Oxygen Balance in the Heart
Angina pectoris results from an imbalance between myocardial oxygen supply and demand. Anti-anginal agents work by dilating blood vessels, reducing cardiac workload, and improving coronary perfusion.
Vasodilators: Fast Relief Through Nitric Oxide Release
Organic nitrates remain the cornerstone for immediate angina relief due to their ability to release nitric oxide and relax vascular smooth muscles.
Amyl nitrite, a fast-acting inhalational vasodilator, is used during acute anginal attacks.
Nitroglycerin, available as sublingual tablets, sprays, and patches, is one of the most widely used drugs for both acute and chronic angina.
Pentaerythritol tetranitrate and Isosorbide dinitrate offer longer-lasting effects for chronic management.
Dipyridamole, though primarily an antiplatelet agent, improves coronary blood flow and is sometimes used in angina prophylaxis.
These vasodilators enhance oxygen delivery to the heart, offering rapid symptomatic relief and improved quality of life for patients.
Calcium Channel Blockers: Reducing Cardiac Workload and Vasospasm
Calcium channel blockers (CCBs) inhibit the entry of calcium ions into cardiac and vascular smooth muscle cells, leading to decreased contractility and vasodilation. They are essential in both angina and hypertension management.
Key CCBs include:
Verapamil – a potent cardiac depressant used in arrhythmias and angina.
Diltiazem hydrochloride – offers balanced effects on the heart and vessels, making it ideal for chronic stable angina.
Bepridil hydrochloride – a long-acting agent with broad antiarrhythmic properties.
Nifedipine, Amlodipine, Felodipine, Nicardipine, Nimodipine – dihydropyridines primarily causing peripheral vasodilation.
These agents reduce both afterload and coronary vasospasm, preventing chest pain and improving blood flow during exertion.
Diuretics: Controlling Fluid Overload and Supporting Blood Pressure Management
Diuretics promote urine formation by acting on different segments of the renal tubules. They are widely used in hypertension, heart failure, edema, and certain renal disorders.
Carbonic Anhydrase Inhibitors
These drugs inhibit carbonic anhydrase enzyme in the proximal tubule, reducing bicarbonate reabsorption.
Acetazolamide – used in glaucoma, altitude sickness, and metabolic alkalosis.
Methazolamide and Dichlorphenamide – newer variants with similar therapeutic roles.
Thiazide Diuretics
Thiazides block sodium–chloride transport in the distal convoluted tubule and are first-line agents for hypertension.
Examples include:
Chlorthiazide – the earliest thiazide developed.
Hydrochlorothiazide – commonly used in fixed-dose antihypertensive combinations.
Hydroflumethiazide and Cyclothiazide – effective in edema and hypertension.
Thiazides are known for their gentle yet sustained diuretic effect.
Loop Diuretics
These act on the Loop of Henle and produce potent diuresis.
Furosemide – widely used in acute pulmonary edema and heart failure.
Bumetanide – more potent than furosemide.
Ethacrynic acid – a non-sulfonamide option for patients allergic to sulfa drugs.
Potassium-Sparing Diuretics
These prevent potassium loss by acting on the distal nephron.
Spironolactone – an aldosterone antagonist useful in heart failure and hyperaldosteronism.
Triamterene and Amiloride – inhibit sodium channels directly.
Osmotic Diuretics
These increase osmotic pressure in the renal tubule.
Mannitol – essential in reducing intracranial pressure and managing acute renal failure.
Together, these diuretics play vital roles in fluid control, electrolyte balance, and cardiovascular stabilization.
Antihypertensive Agents: Modern Tools for Blood Pressure Control
Hypertension is a silent threat requiring long-term pharmacological intervention. Unit 2 covers several well-established antihypertensive classes.
Beta-Blockers
Timolol – used in hypertension and glaucoma due to its reduction of aqueous humor production.
ACE Inhibitors
These drugs inhibit angiotensin-converting enzyme, reducing vasoconstriction and fluid retention.
Notable examples include:
Captopril – the first ACE inhibitor, rapidly absorbed.
Lisinopril, Enalapril, Benazepril, and Quinapril – widely prescribed for hypertension and heart failure.
Centrally Acting Agents
These reduce sympathetic outflow from the brain.
Methyldopate hydrochloride – preferred in pregnancy-related hypertension.
Clonidine hydrochloride – also used in withdrawal syndromes.
Guanabenz acetate and Guanethidine monosulphate – powerful agents reserved for resistant hypertension.
Direct Vasodilators
These drugs relax vascular smooth muscle directly.
Hydralazine hydrochloride – useful in hypertensive emergencies and pregnancy.
Minoxidil – a potent vasodilator also known for stimulating hair growth.
Diazoxide – rapidly reduces blood pressure in emergencies.
Sodium nitroprusside – an IV drug providing immediate, controlled vasodilation.
Reserpine
A classic antihypertensive that depletes catecholamines, though used sparingly today due to side effects.