Cardiovascular profile of oxodipine, a novel dihydropyridine calcium channel blocker, in anesthetized open-chest dogs: a comparison with nitrendipine.

The cardiovascular effects of oxodipine, a new dihydropyridine calcium channel blocker, were studied after i.v. administration to chloralose-anesthetized dogs, and compared with those of nitrendipine. Nitrendipine produced more marked decreases than oxodipine in both systolic and diastolic blood pressure and in total peripheral resistance. No significant modification of heart rate was observed. Oxodipine decreased cardiac contractility, whereas nitrendipine increased it. This difference originated in reflex modifications, since both drugs, administered at doses of 30 and 60 micrograms/kg, decreased cardiac contractility during studies performed after cardiac autonomic blockade. Under these conditions, nitrendipine decreased heart rate, whereas oxodipine had no effect. The two drugs showed comparable effects on coronary and femoral vascular resistance. However, oxodipine caused a very marked persistent decrease of vertebral vascular resistance. On this local circulation, nitrendipine had a weak effect. The results from the present study indicate that oxodipine predominantly increases vertebral blood flow with a concomitant hypertension which is more moderate than after nitrendipine.