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 |
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 | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
NSAIDs may diminish the antihypertensive effect Lithium levels may be increased Risk of neutropenia and agranulocytosis particularly in renal impairment.
| Breastfeeding | Captopril is excreted into breast milk in low concentrations. M/P ratio not established. Compatible with breastfeeding due to low oral bioavailability and minimal infant exposure, but monitor infant for hypotension and renal effects. |
| 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. |
■ 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 therapy","Pregnancy (second and third trimesters)","Concomitant use with aliskiren in patients with diabetes"]
| 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…
| 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. |