====== Captopril ======

Captopril is the first ACE inhibitor developed and is a short-acting agent used in hypertension, heart failure, and post–myocardial infarction care.

Class:
→ [[cardio:raas:acei|ACE Inhibitors]]

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===== Mechanism of Action =====

• Inhibits Angiotensin-Converting Enzyme (ACE)
• ↓ Angiotensin II
• ↓ Aldosterone
• ↑ Bradykinin

Net Effects:
• ↓ Systemic vascular resistance (afterload)
• Mild ↓ preload
• ↓ Ventricular remodeling
• ↓ Blood pressure

Mechanism identical to other ACE inhibitors.

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===== Unique Features =====

• Short half-life (requires multiple daily dosing)
• Active drug (not a prodrug)
• Contains sulfhydryl group (↑ certain side effects)
• Rapid onset — sometimes used in hypertensive urgency

Because of short duration, less commonly used for chronic outpatient therapy compared to lisinopril or enalapril.

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===== Indications =====

==== Hypertension ====
• Effective but requires 2–3 times daily dosing

→ [[cardio:hypertension:start|Hypertension Module]]

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==== Heart Failure (HFrEF) ====
• Mortality benefit demonstrated in early ACE trials
• Less convenient than longer-acting ACE inhibitors

→ [[cardio:heart_failure:start|Heart Failure Module]]

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==== Post-Myocardial Infarction ====
• Reduces ventricular remodeling
• Improves survival (SAVE trial era ACE data)

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===== Dosing =====

Hypertension:
• Start: 12.5–25 mg 2–3 times daily
• Usual range: 25–50 mg 2–3 times daily

Heart Failure:
• Start: 6.25–12.5 mg three times daily
• Target: 50 mg three times daily (if tolerated)

Short duration → typically dosed three times daily.

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===== Pharmacokinetics =====

• Active drug (no hepatic activation required)
• Renally cleared
• Half-life ~2 hours
• Rapid onset of action

Dose adjustment required in renal impairment.

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===== Adverse Effects =====

Class Effects:
• Dry cough
• Hyperkalemia
• Hypotension
• Angioedema (rare)

Unique/More Common with Captopril:
• Rash
• Dysgeusia (altered taste)
• Rare neutropenia (historical high-dose issue)

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===== Monitoring =====

Monitor:
• Serum creatinine
• Potassium

Recheck labs 1–2 weeks after initiation or dose adjustment.

Mild creatinine increase is expected.

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===== Contraindications =====

• Pregnancy
• History of ACE inhibitor–induced angioedema
• Bilateral renal artery stenosis

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===== Clinical Pearls =====

✔ First ACE inhibitor developed  
✔ Short-acting (TID dosing)  
✔ Useful when rapid titration needed  
✔ More taste disturbance than other ACE inhibitors  
✔ Less commonly used long-term due to dosing frequency  

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Related:

→ [[cardio:raas:acei|ACE Inhibitors]]
→ [[cardio:raas:lisinopril|Lisinopril]]
→ [[cardio:raas:enalapril|Enalapril]]
→ [[cardio:start|Return to CV Modules]]