[Effects of benidipine hydrochloride (Coniel) on blood pressure, heart rate and plasma norepinephrine concentration in spontaneously hypertensive rats].

We investigated the effects of benidipine hydrochloride (benidipine, Coniel) on blood pressure, heart rate and plasma norepinephrine (NE) concentration in spontaneously hypertensive rats and compared them with those of other calcium channel blockers. Benidipine (2 mg/kg, p.o.) was compared with the equihypotensive doses of nifedipine (5 mg/kg), cilnidipine (6 mg/kg) and amlodipine (3 mg/kg). All the 4 calcium channel blockers exhibited significant antihypertensive effects. Nifedipine and cilinidipine significantly increased heart rate, as compared with that in the control group, whereas benidipine or amlodipine did not significantly affect it. The area under the curves for hypotensive effect and tachycardic effect for 10 hr after the drug administration were compared among the 4 compounds. As a result, the tachycardic effect of benidipine was significantly lower than those of nifedipine, cilnidipine and amlodipine, while the hypotensive effects were similar among the 4 compounds. Nifedipine and amlodipine, significantly increased plasma NE concentration, cilnidipine tended to increase it. In contrast, benidipine did not significantly affect plasma NE concentration. These results suggest that the effects of benidipine on plasma NE concentration and heart rate are less prominent than those of the other calcium channel blockers.