Angina Pectoris refers to chest pain resulting from myocardial ischemia due to reduced blood flow to the heart muscle.
Anti-anginal drugs aim to relieve and prevent angina by improving myocardial oxygen supply or reducing demand.
Major Classes of Anti-Anginal Drugs
1) Nitrates
Examples: Nitroglycerin, Isosorbide Mononitrate, Isosorbide Dinitrate
MOA: Donate nitric oxide (NO), causing vasodilation of veins (reducing preload) and arteries (reducing afterload).
Benefits: Provide rapid relief of acute angina and prevent anginal episodes.
Side Effects: Headache, hypotension, reflex tachycardia, tolerance with continuous use.
Considerations: Implement a nitrate-free interval to prevent tolerance development.
2) Beta-Blockers
Examples: Metoprolol, Atenolol, Propranolol
MOA: Decrease heart rate, contractility, and myocardial oxygen demand by blocking β-adrenergic receptors.
Benefits: Prevent angina and improve survival in patients with coronary artery disease.
Side Effects: Bradycardia, fatigue, bronchoconstriction.
Considerations: Use with caution in patients with asthma or diabetes.
3) Calcium Channel Blockers
Examples: Diltiazem, Verapamil, Amlodipine, Nifedipine
Subclasses:
A) Dihydropyridines
Examples: Amlodipine, Nifedipine
MOA: Predominantly vasodilatory, reducing afterload by blocking L-type calcium channels in vascular smooth muscle.
Benefits: Prevent angina and treat hypertension.
Side Effects: Peripheral edema, flushing.
B) Non-Dihydropyridines
Examples: Diltiazem, Verapamil
MOA: Reduce heart rate and contractility by blocking calcium channels in the heart.
Benefits: Prevent angina and control arrhythmias.
Side Effects: Bradycardia, constipation (verapamil).
4) Ranolazine
Example: Ranexa
MOA: Inhibits the late phase of the inward sodium current in cardiac myocytes, improving myocardial relaxation and reducing diastolic tension.
Benefits: Relieves chronic angina without significant hemodynamic effects.
Side Effects: Dizziness, constipation, headache.
5) Nicorandil
MOA: Acts both as a nitrate, donating nitric oxide (NO) for vasodilation, and as a potassium channel opener, causing additional vasodilation.
Benefits: Prevents and relieves angina.
Side Effects: Headache, hypotension, flushing.
6) Enhancers of Coronary Blood Flow
Examples: Trimetazidine
MOA: Shifts myocardial metabolism from fatty acid oxidation to glucose oxidation, improving metabolic efficiency under ischemic conditions.
Benefits: Improves anginal symptoms and enhances myocardial metabolism.
Side Effects: Nausea, dizziness.
Clinical Considerations:
Combination Therapy: Often used to maximize symptom relief and minimize side effects.
Lifestyle Modifications: Essential for long-term management (e.g., smoking cessation, diet, exercise).
Patient Education: Importance of adherence, recognizing side effects, and proper use of medications (e.g., nitrates).