Pharmacological studies of the antihypertensive effect of nitrendipine.

1,4-Dihydro-2,6-dimethyl-4(3-nitrophenyl)-3,5-pyridine carboxylic acid, 3-ethyl-5-methyl ester (nitrendipine, Bay e 5009) is a new vasodilatory calcium antagonist with pronounced hypertensive efficacy. Doses of 0.3-31.5 mg/kg p.o. lower the blood pressure of rats with spontaneous, renal and desoxycorticosterone acetate (DOCA)-hypertension. Doses of 0.03-10.0 mg/kg p.o. lower the blood pressure of dogs with renal hypertension. The hypotensive effect is about 10 times less in normotensive rats. No increase in tolerance occurred during therapeutic studies lasting 5 weeks in hypertensive rats and several days in hypertensive dogs. There were no signs either of acquired tolerance developing during these studies. Dogs in fentanyl analgesia respond to i.v. administration of 0.001-0.03 mg/kg with a reduction in peripheral vascular resistance and an increase in cardiac output and heart rate. The stroke volume remains unchanged. The vasodilatory effect occurs at different degrees in different vascular beds. The most pronounced increases in vascular flow were measured in the muscular vessels of the hind quarters and in the coronary vessels. The mesenterical, skin and brain blood flows were much less affected.