Double-blind, randomized, multicentre comparison of the effects of amlodipine and perindopril on 24 h therapeutic coverage and beyond in patients with mild to moderate hypertension

Objective To compare the therapeutic coverage and safety of amlodipine and perindopril in patients with mild to moderate hypertension (diastolic blood pressure greater than or equal to 90 mmHg and less than or equal to 109 mmHg). Design A double-blind, randomized, parallel-group, multicentre study. Methods Following a 2-week placebo wash-out period, the patients were randomly allocated to treatment with either amlodipine at 5-10 mg once a day or perindopril at 4-8 mg once a day, for 60 days. Trough : peak ratios were calculated by two different methods (global and individualized approaches) from 24 h ambulatory blood pressure recordings made after the placebo period and after the active treatment period. Residual lowering of blood pressure after single-blind, single-dose omission was also investigated with further 24 h ambulatory blood pressure monitoring. Safety assessments were made throughout the study. Results The placebo-adjusted, global, diastolic blood pressure trough : peak ratio was 0.80 in the amlodipine group (n = 47) and 0.81 in the perindopril group (n = 49) in an intent-to-treat analysis. The corresponding global systolic blood pressure trough : peak ratio was 0.83 for amlodipine and 0.68 for perindopril. Individual trough : peak ratios were non-normally distributed. Mean (+/- SD) individual trough : peak ratios (intent-to-treat analysis) for diastolic blood pressure were 0.50 +/- 0.69 for amlodipine (median 0.42) and 0.15 +/- 3.27 for perindopril (median 0.33). In the per protocol analysis, the corresponding values were 0.50 +/- 0.72 (median 0.34) for amlodipine and 0.01 +/- 3.90 for perindopril (median 0.21). Both treatments produced comparable decreases in clinic systolic and diastolic blood pressure between days 0 and 60. Forty-eight hours after the last dose, both systolic and diastolic blood pressure were lower in amlodipine-treated patients than perindopril-treated patients. Amlodipine and perindopril were generally well tolerated. The most frequently reported adverse event was leg oedema in amlodipine-treated patients (19.1%), and coughing in perindopril-treated patients (14.3%). Conclusions These results showed no statistically significant difference in trough : peak ratios between amlodipine and perindopril. However, the ambulatory blood pressure trough : peak ratios showed very large variations. Determination of trough : peak ratios by the conventional approach or by an individual approach can yield disparate values. After omitting one dose, a condition imitating noncompliance, blood pressure was more effectively controlled with amlodipine than with perindopril. J Hypertens 1999, 17:137-146 (C) Lippincott Williams & Wilkins.