ONCE-DAILY LISINOPRIL AND CAPTOPRIL IN HYPERTENSION - A DOUBLE-BLIND COMPARISON USING AMBULATORY MONITORING

Aim. To validate and compare the 24-hour antihypertensive efficacy of the angiotensin-converting-enzyme inhibitors, captopril and lisinopril. Methods. A randomised, doubleblind, doubledummy crossover study was performed with single-blind placebo run-in and washout periods and titration opportunities during therapeutic phases (captopril 25mg, 50mg and 100mg daily, lisinopril 10mg, 20mg and 40mg daily). The study was monitored using standard office blood pressure measurements, clinical and laboratory assessment. 24 patients of either sex and between 18 and 70 years with essential hypertension were enrolled, 20 met randomisation criteria (of sitting diastolic pressure 95-115mmHg), 3 withdrew from the study during its active phase and one was excluded from analysis having been found retrospectively to have not met randomisation criteria at the appropriate visit. Predetermined endpoints were blood pressure levels during different time periods of ambulatory monitoring performed at the end of each placebo or treatment phase. Results. In the 17 patients who completed the protocol, lisinopril produced a greater reduction of blood pressure at all time periods although the differences were not all statistically significant. The differences were most marked 19-24 hours post dosage time when pressures (systolic/diastolic) during lisinopril therapy were lower than during captopril by 18.0/14.5 mmHg (p<0.001 for both). As measured by clinic pressures, lisinopril also achieved a considerably higher degree of blood pressure control with less dose titration. Conclusion. In this study, lisinopril proved a more effective once daily antihypertensive agent than captopril, especially in the last 6 hours of the 24-hour dosage interval.