CAPTOPRIL
Clinical safety rating: avoid
Contraindicated (not allowed)
Competitive inhibitor of angiotensin-converting enzyme (ACE), preventing conversion of angiotensin I to angiotensin II, reducing vasoconstriction and aldosterone secretion.
| Metabolism | Hepatic via unidentified pathways; approximately 50% of total clearance is renal. |
| Excretion | Primarily renal (50-60% unchanged), with minor biliary/fecal elimination (<5%) |
| Half-life | Terminal half-life 1.9 hours, prolonged to 3.5-32 hours in renal impairment; clinical context: requires adjusted dosing in renal failure |
| Protein binding | 25-30% bound to albumin (primarily) and other plasma proteins |
| Volume of Distribution | 0.7 L/kg; moderate tissue distribution, suggesting limited extravascular penetration |
| Bioavailability | Oral: 65-75% (reduced by food); variable due to first-pass metabolism |
| Onset of Action | Oral: 15-30 minutes for reduction in blood pressure; clinical effect peak at 60-90 minutes |
| Duration of Action | Duration 6-12 hours for antihypertensive effect, though dose-dependent; may require twice-daily dosing |
| Molecular Weight | 217.29 |
Initial: 25 mg PO 2-3 times daily; target dose: 50 mg PO 2-3 times daily; maximum: 450 mg/day. For heart failure: start 6.25-12.5 mg PO 3 times daily, titrate to 25-50 mg PO 3 times daily.
| Dosage form | TABLET |
| Renal impairment | CrCl 10-50 mL/min: 75% of dose; CrCl <10 mL/min: 50% of dose. Hemodialysis: administer after dialysis, supplement 25-50% of dose. |
| Liver impairment | No specific guidelines; use with caution in severe hepatic impairment. Monitor liver function. |
| Pediatric use | Neonates: 0.01-0.2 mg/kg/dose PO every 8-24 hours. Infants and children: initial 0.3-0.5 mg/kg/dose PO every 8 hours, titrate to maximum 6 mg/kg/day. Hypertension: 0.3-0.5 mg/kg/dose PO every 8 hours. |
| Geriatric use | Elderly: start lower dose (e.g., 6.25 mg PO 2-3 times daily) due to decreased renal function and increased sensitivity. Monitor blood pressure and electrolytes closely. |
| 1st trimester | Contraindicated during first trimester due to risk of fetal renal dysfunction, oligohydramnios, and skull ossification defects. Use only if no alternative and patient is informed of risks. |
| 2nd trimester | Contraindicated. Associated with fetal hypotension, anuria, and renal failure. Avoid use due to high risk of fetal injury. |
| 3rd trimester | Contraindicated. High risk of neonatal hypotension, anuria, and persistent pulmonary hypertension. Avoid use in third trimester. |
Clinical note
NSAIDs may diminish the antihypertensive effect Lithium levels may be increased Risk of neutropenia and agranulocytosis particularly in renal impairment.
| Placental transfer | Captopril crosses the placenta. Fetal exposure is approximately 100% of maternal plasma levels based on animal and human data. Detected in fetal tissue and amniotic fluid. |
| Breastfeeding | Captopril is excreted into breast milk in low concentrations. Because of the potential for adverse effects in the nursing infant (especially renal and hypotensive effects), use with caution only if clearly indicated. Monitor infant for hypotension and renal function. |
■ FDA Black Box Warning
Use during pregnancy, especially in the second and third trimesters, can cause fetal injury and death. Discontinue as soon as pregnancy is detected.
| Common Effects | heart failure |
| Serious Effects |
History of angioedema related to previous ACE inhibitor therapyConcurrent use with aliskiren in patients with diabetes mellitusPregnancy (contraindicated in all trimesters)Hypersensitivity to captopril or any ACE inhibitor
| Precautions | Angioedema, Hypotension, Hyperkalemia, Renal impairment, Cough, Neutropenia/agranulocytosis, Hepatic failure, Symptomatic hypotension in volume-depleted patients |
| Food/Dietary | Avoid high-potassium foods (e.g., bananas, oranges, potatoes, spinach, salt substitutes with potassium). Take captopril at least 1 hour before meals as food reduces absorption. Limit alcohol intake due to additive hypotensive effects. |
Loading safety data…
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | First trimester: Epidemiological data suggest potential increased risk of congenital malformations, particularly cardiovascular and central nervous system defects, though absolute risk is low. Second and third trimesters: Fetal oligohydramnios, neonatal renal dysfunction, skull ossification defects, and hypotension. Exposure after 20 weeks is associated with oligohydramnios sequence including limb contractures, pulmonary hypoplasia, and neonatal anuria. |
| Fetal Monitoring | Maternal: Blood pressure, renal function, serum electrolytes, and complete blood count. Fetal: Ultrasound for amniotic fluid volume and fetal growth if used in second/third trimester. Neonatal: Monitor blood pressure and renal function after delivery. |
| Fertility Effects | No significant adverse effects on fertility reported in clinical studies. Animal studies show no impairment of fertility at therapeutic doses. |
| Clinical Pearls | Use with caution in renal artery stenosis; monitor renal function and potassium levels. First-dose hypotension may occur, especially in volume-depleted patients. Adjust dose in renal impairment (CrCl <30 mL/min). Avoid in pregnancy (category D). |
| Patient Advice | Take captopril on an empty stomach (1 hour before meals) for best absorption. · Do not use salt substitutes containing potassium without consulting your doctor. · Report any signs of infection (sore throat, fever) or swelling of face/extremities (angioedema) immediately. · You may experience dizziness during the first few doses; rise slowly from sitting or lying positions. · This medication can cause a dry, persistent cough; inform your doctor if it becomes bothersome. |