Effect of evening versus morning benazepril on 24-hour blood pressure: a comparative study with continuous intraarterial monitoring

In a single-blind, in-patient, crossover study, the influence on the circadian blood pressure (BP) profile of the 9:00 a.m. versus the 9:00 p.m. acute administration of a single dose of benazepril 10 mg, a new angiotensin-converting-enzyme inhibitor, was assessed in 10 hypertensive patients by means of 24-hour intraarterial ambulatory BP monitoring. Mean 24-hour BP for the three treatments (placebo, benazepril a.m., benazepril p.m.) were 155/93, 131/83 and 138/86 mmHg, respectively. No significant differences between the two benazepril schedules were found in terms of either 24-hour or day-time and night-time mean BP values. However, hourly averages showed that benazepril a.m. had a more sustained antihypertensive effect than benazepril p.m., where a loss of efficacy was observed 19 hours after the administration. BP responses to static and dynamic exercise and to cold pressor test were unchanged after both benazepril schedules, as were BP peaks. These results demonstrate that acute benazepril administration markedly reduces systolic and diastolic BP. The morning administration is preferable because it more effectively covers the whole 24 hours than an evening dose.