The hemodynamic effects of lacidipine in anesthetized dogs: comparison with nitrendipine, amlodipine, verapamil, and diltiazem.

The hemodynamic effects of lacidipine in anesthetized, open-chest dogs were compared with those of nitrendipine, amlodipine, verapamil and diltiazem. Lacidipine administered intravenously induced dose-related, long-lasting reductions in systemic and coronary vascular resistance with corresponding increases in aortic flow and coronary blood flow. The hypotensive effect (ED25 for mean blood pressure reduction = 0.006 mg/kg) was still significant 120 min after administration with all doses tested. Nitrendipine was equipotent with lacidipine in reducing the mean blood pressure (ED25 = 0.005 mg/kg), but its effect was shorter acting (significant effect at 120 min only with the highest dose tested). Amlodipine caused a marked and long-lasting hypotension though at higher doses than lacidipine (ED25 = 0.50 mg/kg). Short-lasting hypotensive responses were also detected with verapamil (ED25 = 0.1 mg/kg) and diltiazem (ED25 = 0.12 mg/kg). A reflex increase in heart rate was observed with lacidipine, nitrendipine, and amlodipine, whereas verapamil and diltiazem showed a dose-related bradycardia. No effect on AV conduction was observed with lacidipine and nitrendipine, whereas amlodipine, verapamil, and diltiazem produced second- to third-degree AV block at the highest doses tested. Lacidipine and nitrendipine caused a reflex increase in contractile index at all doses, whereas amlodipine was more similar to verapamil since a marked decrease in contractile index was detected at the highest dose. Diltiazem was practically devoid of negative inotropic effect.