Pharmacological studies of a newly synthetized 1,4-dihydropyridine derivative, 2,6-dimethyl-3,5-dimethoxycarbonyl-4- (o-difluoromethoxyphenyl)-1,4-dihydropyridine (PP-1466).

Hemodynamic effects of a new 1,4-dihydropyridine derivative, 2,6-dimethyl-3,5-dimethoxycarbonyl-4-(o-difluoromethoxyphenyl++ +)-1,4-dihydropyridine (PP-1466), were examined by measuring systemic blood pressure, various arterial blood flow such as femoral, vertebral, renal and superior mesenteric artery, heart rate and respiratory rate in anesthetized dogs. Cardiohemodynamic effects were examined by measuring cardiac output, coronary blood flow, maximal rate of rise of left ventricular pressure (dp/dt max.) and right atrial pressure. The changes in myocardial oxygen consumption associated with the parameters mentioned above were also examined by measuring coronary sinus outflow and oxygen content in blood samples. The results obtained are as follows: The intraarterial administration of PP-1466 to the femoral artery caused vasodilating response. The vasodilating effect of PP-1466 was approximately 200 times more potent than that of papaverine and comparable to that of nifedipine or nicardipine (YC-93). The effective dose to induce vasodilation on femoral, vertebral and superior mesenteric artery by the systemic use of PP-1466 was more than 0.3 microgram/kg i.v. and more than 0.03 mg/kg i.d. The vasodilation in vertebral artery was most prominent. After intravenous administration of PP-1466, renal blood flow decreased probably due to the fall in systemic blood pressure, whereas the flow progressively increased after intraduodenal administration. The effective dose to induce a fall in systemic blood pressure by PP-1466 was the range from 1 to 3 micrograms/kg i.v. and more than 0.1 mg/kg i.d., respectively. Diastolic hypotension was remarkable. Heart rate and respiratory rate were increased at the same time.(ABSTRACT TRUNCATED AT 250 WORDS)