Comparison of enalapril to captopril by 24-hour ambulatory blood pressure monitoring

The efficacy of a once-daily dose of enalapril was compared with a thrice-daily dose of captopril in an open-label, randomized parallel group study of 27 hypertensive patients. The patients were monitored using conventional measurements of blood pressure and with 24-hour ambulatory blood pressure monitoring at baseline and after 12 weeks of therapy. The end points were 24-hour, daytime, and nighttime mean blood pressure values and the percentage of elevated systolic and diastolic measurements, reflecting the ''hypertensive load.'' Enalapril reduced mean 24-hour systolic blood pressure by 18 mmHg and diastolic blood pressure by 11 mmHg. The comparative values for captopril were 9 mmHg and 2 mmHg, respectively. The mean daytime systolic blood pressure was reduced by 20 mmHg with enalapril versus 7 mmHg with captopril; the diastolic values were lowered by 11 mmHg with enalapril versus 4 mmHg with captopril. The mean nighttime systolic blood pressure was lowered by 16 mmHg with enalapril versus 12 mmHg with captopril; the diastolic values were reduced by 10 mmHg with enalapril and 5 mmHg with captopril. No major side effects were recorded in either group. A single daily 20-mg dose of enalapril, therefore, proved to be equipotent or superior to 75 mg of captopril administered in three divided doses.