Effects of semotiadil fumarate, a novel calcium antagonist, on blood pressure and heart rate in conscious spontaneously hypertensive rats.

The acute antihypertensive effects of orally administered semotiadil, a novel calcium antagonist, were compared with those of nifedipine and diltiazem in conscious, unrestrained spontaneously hypertensive rats (SHRs). Semotiadil (10 and 30 mg/kg) produced a dose-dependent hypotension that persisted for 18 hr at 30 mg/kg. Diltiazem (30 and 100 mg/kg) and nifedipine (1 and 3 mg/kg) also exhibited hypotension dose-dependently, but their durations of actions were shorter than that of semotiadil. Semotiadil caused a slight increase in heart rate, while diltiazem and nifedipine caused a bradycardia and a marked tachycardia, respectively. These results suggest that semotiadil has a beneficial property as an antihypertensive drug.