Drugs Acting on the Cardiovascular System and Blood Disorders

Alumkal

Introduction

  • The cardiovascular system consists of the heart, blood vessels, and blood, and it is responsible for transporting oxygen, nutrients, hormones, and metabolic waste products throughout the body.

  • Disorders of the cardiovascular system include hypertension, angina pectoris, heart failure, edema, and blood circulation abnormalities.

  • To manage these conditions, several groups of drugs are used that act directly or indirectly on the heart, blood vessels, and kidneys.

  • Important categories of cardiovascular drugs include anti-hypertensive drugs, antianginal drugs, diuretics, cardiac glycosides, anticoagulants, and lipid-lowering agents.

  • Among these, anti-hypertensives, antianginal drugs, and diuretics are widely used in clinical practice.

  • These drugs work through different mechanisms such as reducing blood pressure, improving blood flow to the heart, decreasing cardiac workload, and removing excess fluid from the body.

  • Understanding the classification, mechanism of action, therapeutic uses, side effects, and adverse effects of these drugs is essential for proper treatment and safe drug therapy.

 

Anti-Hypertensive Drugs

Anti-hypertensive drugs are medications used to lower elevated blood pressure (hypertension) and reduce the risk of complications such as stroke, heart attack, and kidney failure.

Classification of Anti-Hypertensive Drugs

Class Examples Mechanism
Diuretics Hydrochlorothiazide, Furosemide Increase sodium and water excretion
ACE inhibitors Enalapril, Captopril Inhibit formation of angiotensin II
Angiotensin receptor blockers (ARBs) Losartan, Valsartan Block angiotensin II receptors
Beta blockers Atenolol, Propranolol Reduce heart rate and cardiac output
Calcium channel blockers Amlodipine, Verapamil Relax blood vessels
Vasodilators Hydralazine, Minoxidil Direct relaxation of vascular smooth muscle

Mechanism of Action

  • Reduce peripheral vascular resistance.

  • Decrease cardiac output.

  • Promote excretion of sodium and water.

  • Block hormonal pathways involved in blood pressure regulation.

Therapeutic Uses

  • Treatment of essential hypertension.

  • Prevention of stroke and myocardial infarction.

  • Management of heart failure.

  • Protection of kidney function in diabetic patients.

Side Effects

  • Dizziness

  • Headache

  • Fatigue

  • Hypotension

  • Dry cough (ACE inhibitors)

Adverse Effects

  • Severe hypotension

  • Electrolyte imbalance

  • Kidney dysfunction

  • Bradycardia (with beta blockers)

 

Antianginal Drugs

Antianginal drugs are medications used to relieve or prevent angina pectoris, which is chest pain caused by reduced blood supply to the heart muscle.

Causes of Angina

  • Coronary artery disease

  • Atherosclerosis

  • Increased cardiac workload

  • Reduced oxygen supply to myocardium

Classification of Antianginal Drugs

Class Examples Mechanism
Nitrates Nitroglycerin, Isosorbide dinitrate Dilate coronary arteries
Beta blockers Atenolol, Metoprolol Reduce heart rate and oxygen demand
Calcium channel blockers Amlodipine, Diltiazem Relax coronary vessels
Potassium channel openers Nicorandil Improve blood flow to heart

Mechanism of Action

  • Dilate coronary arteries, improving oxygen supply to the heart.

  • Reduce myocardial oxygen demand by lowering heart rate and contractility.

  • Decrease preload and afterload, reducing cardiac workload.

Therapeutic Uses

  • Treatment of stable angina.

  • Prevention of angina attacks.

  • Management of coronary artery disease.

  • Used in acute angina emergencies.

Side Effects

  • Headache

  • Flushing

  • Dizziness

  • Hypotension

Adverse Effects

  • Severe drop in blood pressure

  • Reflex tachycardia

  • Drug tolerance (with prolonged nitrate use)

 

Diuretics

Diuretics are drugs that increase urine production, promoting the removal of excess water and sodium from the body.

Classification of Diuretics

Type Examples Site of Action
Thiazide diuretics Hydrochlorothiazide Distal convoluted tubule
Loop diuretics Furosemide Loop of Henle
Potassium-sparing diuretics Spironolactone, Amiloride Distal tubule
Osmotic diuretics Mannitol Proximal tubule and loop

Mechanism of Action

  • Increase excretion of sodium and water.

  • Reduce blood volume.

  • Decrease blood pressure and cardiac workload.

Therapeutic Uses

  • Treatment of hypertension.

  • Management of edema in heart failure.

  • Treatment of kidney disease.

  • Reduction of intracranial pressure (mannitol).

  • Management of pulmonary edema.

Side Effects

  • Frequent urination

  • Weakness

  • Muscle cramps

  • Increased thirst

Adverse Effects

  • Electrolyte imbalance (hypokalemia or hyperkalemia)

  • Dehydration

  • Kidney dysfunction

  • Metabolic disturbances

 

Comparison of Major Cardiovascular Drugs

Drug Group Main Function Examples Major Use
Anti-hypertensives Lower blood pressure Enalapril, Atenolol Hypertension
Antianginal drugs Improve blood supply to heart Nitroglycerin Angina
Diuretics Remove excess fluid Furosemide, Mannitol Edema and hypertension

 

General Precautions in Cardiovascular Drug Therapy

  • Monitor blood pressure regularly during treatment.

  • Maintain proper electrolyte balance.

  • Avoid abrupt withdrawal of beta blockers.

  • Use nitrates carefully to prevent severe hypotension.

  • Monitor kidney function during diuretic therapy.

  • Follow lifestyle modifications such as low-salt diet and regular exercise.