Captopril

# Captopril ## Overview - **Classification**: Angiotensin-Converting Enzyme (ACE) Inhibitor - **Mechanism**: Blocks the conversion of angiotensin I to angiotensin II, leading to vasodilation, reduced aldosterone secretion, and decreased sodium/water retention. ## Primary Indications 1. **Hypertension** - Treatment of high blood pressure. 2. **Heart Failure (CHF)** - Management of symptomatic heart failure. 3. **Left Ventricular Dysfunction Post-MI** - To improve survival post-myocardial infarction. 4. **Diabetic Nephropathy** - Slows progression of renal disease in Type 1 diabetics. ## Adult Dosing ### Standard Dosing **Hypertension** - **Dose**: Initial **12.5 mg** PO - **Frequency**: Two to three times daily - **Route**: Oral - **Maximum**: **450 mg/day** **Heart Failure** - **Dose**: Initial **6.25 mg** to **12.5 mg** PO - **Frequency**: Three times daily - **Route**: Oral - **Maximum**: **450 mg/day** (maintenance typically **50-100 mg** TID) **Left Ventricular Dysfunction Post-MI** - **Dose**: Initial **6.25 mg** PO (start 2 days post-MI) - **Frequency**: Then **12.5 mg** PO TID, target **50 mg** PO TID - **Route**: Oral **Diabetic Nephropathy** - **Dose**: Initial **25 mg** PO - **Frequency**: Three times daily - **Route**: Oral - **Maximum**: **100 mg/day** ### Dose Adjustments - **Renal Impairment**: Reduce dose and/or extend interval. - CrCl 21-50 mL/min: Start at **75%** of usual dose. - CrCl <20 mL/min: Start at **50%** of usual dose. - **Hepatic Impairment**: Use with caution; monitor liver function. No specific dose adjustments. - **Elderly Patients**: Start with lower doses (e.g., **6.25 mg** BID-TID) due to potential reduced renal function. ## Pediatric Dosing ### Neonates (0-28 days) - **Dose**: Initial **0.05-0.1 mg/kg** PO - **Frequency**: Every 6 to 24 hours - **Maximum**: **0.5 mg/kg/dose** or **3.5 mg/kg/day** - **Special Notes**: High risk of hypotension and renal dysfunction. Close BP and renal monitoring required. ### Infants (1-12 months) - **Dose**: Initial **0.15-0.3 mg/kg** PO - **Frequency**: Two to three times daily - **Maximum**: **0.5 mg/kg/dose** (up to **50 mg/dose**) or **6 mg/kg/day** (up to **150 mg/day**) ### Children (1-12 years) - **Dose**: Initial **0.3-0.5 mg/kg** PO - **Frequency**: Two to three times daily - **Maximum**: **1.5 mg/kg/dose** (up to **50 mg/dose**) or **6 mg/kg/day** (up to **150 mg/day**) ### Adolescents (13-18 years) - **Dose**: Follow adult dosing guidelines. Initial **12.5 mg** PO BID-TID. - **Maximum**: **450 mg/day**. ## Safety Information ### Contraindications - **Absolute**: History of angioedema related to ACE inhibitor therapy. - **Absolute**: Hereditary or idiopathic angioedema. - **Absolute**: Concomitant use with aliskiren in patients with diabetes or renal impairment (CrCl <60 mL/min). - **Absolute**: Pregnancy (2nd and 3rd trimesters). - **Relative**: Bilateral renal artery stenosis. ### Common Adverse Effects - **Very Common (>10%)**: Dry, persistent cough; Headache. - **Common (1-10%)**: Dizziness, Hypotension, Fatigue, Taste disturbance (dysgeusia), Hyperkalemia, Rash. - **Serious but Rare**: Angioedema (swelling of face, lips, tongue, throat), Agranulocytosis, Acute renal failure, Hepatic failure. ### Key Drug Interactions - **Potassium-sparing diuretics/Potassium supplements**: Increased risk of hyperkalemia. Monitor serum potassium closely. - **NSAIDs**: May reduce antihypertensive effect and increase risk of renal impairment. Monitor renal function. - **Lithium**: May increase lithium levels, leading to toxicity. Monitor lithium levels. - **Aliskiren**: Contraindicated in specific populations (see Contraindications). Increases risk of adverse effects. - **Other RAAS inhibitors (ARBs, direct renin inhibitors)**: Not recommended due to increased adverse events. ## Monitoring & Follow-up - **Before Treatment**: Baseline blood pressure (BP), renal function (SCr, BUN), electrolytes (K+). - **During Treatment**: Monitor BP regularly, especially after initial dose or dose increases. - **During Treatment**: Renal function (SCr, BUN) and electrolytes (K+) within 1-2 weeks, then periodically. - **Clinical Signs**: Watch for signs of angioedema (swelling), persistent cough, orthostatic hypotension, or symptoms of hyperkalemia. ## Clinical Pearls - 💡 **Tip 1**: Administer **1 hour before meals** for optimal absorption; food reduces bioavailability. - 💡 **Tip 2**: **First-dose hypotension** can occur; consider starting at bedtime or in a supervised setting. - 💡 **Tip 3**: Educate patients on the possibility of a **persistent dry cough** and the signs of angioedema. - 💡 **Tip 4**: Captopril's short half-life necessitates **multiple daily doses**, which can impact adherence. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.