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Drugs, Supplies and Delivery
Captopril
Captopril, the first angiotensin-converting enzyme (ACE) inhibitor, revolutionized hypertension and heart failure management. Approved in the 1980s, it remains a cornerstone therapy due to its efficacy and broad applications. This article synthesizes information from the British National Formulary (BNF), Lippincott Textbook of Pharmacology, and Lange Basic & Clinical Pharmacology to detail its mechanism, uses, dosing, and safety profile.
Captopril inhibits ACE, blocking the conversion of angiotensin I to angiotensin II, a potent vasoconstrictor. By reducing angiotensin II levels, it decreases systemic vascular resistance and aldosterone secretion, promoting vasodilation and sodium/water excretion. Additionally, ACE inhibition increases bradykinin levels, contributing to vasodilation but also side effects like cough (Lippincott, Lange).
- Hypertension: First-line for essential hypertension, often combined with diuretics or calcium channel blockers (BNF).
- Heart Failure (HF): Improves symptoms and survival by reducing afterload and ventricular remodeling (Lange).
- Post-Myocardial Infarction (MI): Mitigates left ventricular dysfunction and remodeling post-MI (BNF).
- Diabetic Nephropathy: Slows progression in type 1 diabetes with proteinuria (Lippincott).
- Hypertension: Start at 12.5–25 mg twice daily, titrating to 50 mg twice daily (max 150 mg/day).
- Heart Failure: Initiate at 6.25 mg thrice daily, gradually increasing to 25–50 mg thrice daily.
- Post-MI: Begin with 6.25 mg, then 50 mg twice daily after 24 hours.
- Renal Impairment: Adjust based on creatinine clearance (e.g., reduce dose if CrCl <30 mL/min) (BNF).
Administration: Take 1 hour before meals to avoid reduced absorption (Lippincott).
- Common: Dry cough (bradykinin-mediated), dizziness, taste disturbances (dysgeusia), hyperkalemia, rash.
- Serious: Angioedema (rare but life-threatening), acute kidney injury, hypotension, neutropenia (BNF, Lange).
- pregnancy: Contraindicated (Category D); risk of fetal renal dysfunction and malformations.
- Renal Artery Stenosis: Avoid in bilateral stenosis due to risk of acute kidney injury.
- Monitoring: Regular serum creatinine, potassium, and blood pressure checks (Lippincott, BNF).
- Diuretics: Synergistic hypotension; avoid concurrent potassium-sparing diuretics (hyperkalemia risk).
- NSAIDs: Reduce antihypertensive effect and worsen renal function.
- Lithium: Increased lithium toxicity risk.
- Allopurinol: Hypersensitivity reactions (Lange, BNF).
Captopril is the generic name globally. Brand names vary (e.g., Capoten®), but generics are widely available.
