Effect of the calcium antagonist benidipine hydrochloride on 24-h ambulatory blood pressure in patients with mild to moderate hypertension in a double-blind study against placebo

The effects of benidipine hydrochloride (benidipine, CAS 91559-74-5), a dihydropyridine calcium antagonist, on the 24-h ambulatory blood pressure were studied by a double-blind test against placebo in 8 patients with essential hypertension. The mean resting systolic (SBP) and diastolic (DBP) blood pressures were 173 mmHg and 104 mmHg, respectively, at the time of patients enrollment. Blood pressure was measured every 30 min for 24 h after a single oral administration of either benidipine (4 mg/day) or the placebo. The mean through/peak (T/P) ratios were calculated from blood pressure measurements obtained using 2-h moving averages, and the smoothness index (SI) was calculated by subtracting the effect of the placebo from that of benidipine at each interval. The mean SBP and DBP fell to 135 and 88 mmHg, respectively, after dosing, which gave T/P ratios of 82% and 64%, respectively. The SIs for SBP and DBP were 1.82 and 0.76, respectively. These findings indicate that benidipine maintained a satisfactory and durable antihypertensive effect by once-a-day dosing.