Time-dependent effects of imidapril administration in patients with morning hypertension measured as home blood pressure

We investigated the effect of the timing of imidapril administration in patients with morning hypertension (home blood pressure [HBP] in the morning [morning HBP] ≥135/85 mmHg). Eighty-seven patients (mean age, 61 years; 48% women) with morning hypertension each measured HBP in the early morning, before going to bed for the final five days of the observation, and during treatment. Imidapril (2.5 or 5.0 mg) was administered once every morning (n = 57) or at bedtime (n = 30) for four weeks (monotherapy: n = 30, 34%; combined with other antihypertensive drugs: n = 57, 66%). The morning (M) versus evening (E) effect (M/E ratio) and the evening versus morning effect (E/M ratio) were calculated to assess the duration of imidapril action. Morning HBP was significantly reduced (all p < 0.05) except when 2.5 mg of imidapril was administered once at bedtime. The individual M/E ratios expressed as means ± standard deviation for systolic HBP were 0.9 ± 0.7 and 0.7 ± 0.7 for the morning administration of 2.5 and 5.0 mg of imidapril, respectively. The corresponding E/M ratios for bedtime administration were 0.3 ± 0.5 and 1.0 ± 0.7, respectively. One daily dose of imidapril taken either in the morning or at bedtime lowered morning HBP, indicating that imidapril is useful for controlling morning hypertension.