Effect of captopril injection in patients with moderate to severe hypertension

The effect of intravenous captopril was studied in 24 white patients who had moderate to severe hypertension. Patients received incremental doses of 1 to 10 mg delivered at 10 min intervals over 50 to 80 min. Blood pressure (BP) was lowered within 5 to 10 min after the initial dose was administered and continued to decline, reaching a maximum response after 20 min (2 to 4 mg). At this time group mean BP fell from 175 +/- 3/111 +/- 1 to 166 +/- 3/97 +/- 2 mm Hg (P less than 0.01). Additional dose increments to an average cumulative dose of 40 mg did not increase the initial effect. No adverse side effects or symptomatic hypotension occurred in any subject. There was a significant correlation between diastolic BP decreases observed in response to intravenous captopril and subsequent long-term oral captopril therapy. The addition of hydrochlorothiazide increased the proportion of patients reaching normotension. We conclude that small intravenous bolus injections of captopril appear to be effective rapidly and are well tolerated in moderate to severe essential hypertension. Short-term intravenous administration seems to predict the response to chronic oral captopril therapy.