Antianginal Drugs_ Osmosis Overview

Antianginal Drugs: Osmosis Overview

Antianginal drugs are a crucial component in the management of coronary artery disease, particularly in treating stable angina pectoris. These medications aim to reduce the frequency and severity of angina attacks by improving the balance between myocardial oxygen supply and demand. Understanding the key concepts of antianginal drugs through an Osmosis-style overview can help solidify your knowledge of this important topic.

Key Concepts:

Pathophysiology of Angina:

Angina results from an imbalance between myocardial oxygen supply and demand

Typically caused by atherosclerotic narrowing of coronary arteries

Symptoms include chest pain, pressure, or discomfort

Goals of Antianginal Therapy:

Reduce myocardial oxygen demand

Increase myocardial oxygen supply

Improve exercise tolerance

Enhance quality of life

Major Classes of Antianginal Drugs:

a) Nitrates:

Mechanism: Release nitric oxide, causing vasodilation

Examples: Nitroglycerin, Isosorbide mononitrate

Effects: Reduce preload, afterload, and coronary vasodilation

Key point: Can develop tolerance with continuous use

b) Beta-Blockers:

Mechanism: Block beta-adrenergic receptors

Examples: Metoprolol, Atenolol

Effects: Reduce heart rate, contractility, and blood pressure

Key point: First-line therapy for many patients with stable angina

c) Calcium Channel Blockers:

Mechanism: Block calcium influx into smooth muscle and cardiac cells

Examples: Amlodipine (dihydropyridine), Diltiazem (non-dihydropyridine)

Effects: Vasodilation, reduce contractility (non-dihydropyridines)

Key point: Useful in patients with concurrent hypertension

d) Newer Antianginal Drugs:

Ranolazine: Inhibits late sodium current

Ivabradine: Selective If channel inhibitor (reduces heart rate)

Nicorandil: Potassium channel opener with nitrate-like effects

Clinical Considerations:

Combination therapy often necessary for optimal symptom control

Consider individual patient factors (comorbidities, contraindications)

Monitor for side effects and adjust therapy as needed

Non-Pharmacological Management:

Lifestyle modifications (smoking cessation, diet, exercise)

Risk factor management (hypertension, diabetes, hyperlipidemia)

Revascularization procedures when appropriate

Pharmacokinetics:

Nitrates: Rapid onset (sublingual), short-acting and long-acting forms

Beta-blockers: Oral administration, varying half-lives

Calcium channel blockers: Oral administration, some with extended-release formulations

Side Effects and Precautions:

Nitrates: Headache, hypotension, tolerance

Beta-blockers: Bradycardia, fatigue, bronchospasm

Calcium channel blockers: Peripheral edema, constipation (verapamil)

Special Populations:

Elderly: Start with lower doses, monitor for side effects

Pregnancy: Beta-blockers generally considered safe, avoid ACE inhibitors

Renal/Hepatic impairment: Dose adjustments may be necessary

Drug Interactions:

Nitrates + PDE5 inhibitors (e.g.