Captopril competitively inhibits the conversion of angiotensin I (ATI) to angiotensin II (ATII), thus resulting in reduced ATII levels and aldosterone secretion. It also increases plasma renin activity and bradykinin levels. Reduction of ATII leads to decreased Na and water retention. This promotes vasodilation and BP reduction.
Adult: Type 1 diabetics: 75-100 mg/day in divided doses.
Adult: May be started 3-16 days after MI. Initially, 6.25 mg/day followed by 12.5 mg tid for 2 days, then 25 mg tid. Maintenance: 75-150 mg/day in 2 or 3 divided doses.
Adult: Initially, 12.5 mg bid, 1st dose preferably at bedtime to avoid precipitous fall in BP, gradually increased at 2-4-wk intervals according to response. Maintenance: 25-50 mg bid. Max: 50 mg tid. Patients on diuretics: 6.25 mg bid.
Child: Neonates and infants: 0.15 mg/kg. Max: 6 mg/kg in 2 or 3 divided doses according to response. Childn and adolescents: 0.3 mg/kg. Max: 6 mg/kg in 2 or 3 divided doses according to response.
Elderly: Initially, 6.25 mg bid.
Adult: Initially, 6.25-12.5 mg bid or tid. Maintenance: 25 mg bid or tid. Max: 50 mg tid.
Child: Initially, 0.25 mg/kg/day, increased up to 2.5 or 3.5 mg/kg/day in 3 divided doses.