Classification of Antianginal Drugs
Nitrates
Mechanism of Action
Nitrates (e.g., nitroglycerin, isosorbide dinitrate) are converted to nitric oxide (NO), leading to vasodilation, primarily venous, which decreases preload and myocardial oxygen demand, and improves blood flow to ischemic areas through coronary dilation.
Therapeutic Uses
- Angina Pectoris
- Heart Failure (as adjunct therapy)
- Acute Myocardial Infarction
- Hypertensive Emergencies
Adverse Effects
- Headache
- Hypotension
- Tachycardia
- Flushing
- Tolerance
- Methemoglobinemia (rare)
Beta-Blockers
Mechanism of Action
Beta-blockers (e.g., metoprolol, atenolol) block β-adrenergic receptors, reducing heart rate, myocardial contractility, and oxygen demand.
Therapeutic Uses
- Stable Angina
- Unstable Angina
- Post-Myocardial Infarction
- Hypertension
Adverse Effects
- Bradycardia
- Fatigue
- Hypotension
- Bronchospasm (in asthmatic patients)
Calcium Channel Blockers
Mechanism of Action
Calcium channel blockers (e.g., amlodipine, diltiazem) inhibit calcium influx into vascular smooth muscle and cardiac cells, leading to vasodilation and decreased myocardial contractility.
Therapeutic Uses
- Stable Angina
- Variant Angina (Prinzmetal's angina)
- Hypertension
Adverse Effects
- Peripheral Edema
- Hypotension
- Bradycardia (with non-dihydropyridines)
Cytoprotective Agents
Mechanism of Action
Cytoprotective agents (e.g., trimetazidine) enhance glucose oxidation and maintain ATP levels in myocardial cells, providing metabolic protection during ischemia.
Therapeutic Uses
- Stable Angina (as an adjunct therapy)
- Myocardial Ischemia
Adverse Effects
- Gastrointestinal Disturbances
- Dizziness
- Parkinsonism-like symptoms (rare)
Potassium Channel Openers
Mechanism of Action
Potassium channel openers (e.g., nicorandil) induce hyperpolarization of vascular smooth muscle cells, leading to vasodilation and reduced myocardial oxygen demand.
Therapeutic Uses
- Angina Pectoris
- Hypertension
Adverse Effects
- Headache
- Flushing
- Hypotension
- Gastrointestinal Upset
Miscellaneous Agents
Ranolazine
Mechanism of Action
Ranolazine works by inhibiting the late sodium current, reducing intracellular calcium overload and myocardial oxygen consumption.
Therapeutic Uses
- Chronic Stable Angina (can be used in combination with other agents)
Adverse Effects
- Dizziness
- Constipation
- Nausea
- QT Prolongation (rarely)
If Current Inhibitors
Ivabradine
Mechanism of Action
Ivabradine selectively inhibits the If current (funny current) in the sinoatrial node, leading to decreased heart rate without affecting myocardial contractility or blood pressure.
Therapeutic Uses
- Chronic Stable Angina
- Heart Failure (in patients with elevated heart rate despite beta-blocker therapy)
Adverse Effects
- Bradycardia
- Visual disturbances (phosphenes)
- Atrial Fibrillation
- Dizziness
