pranidipine and Hypertension--Renovascular

The antihypertensive action of OPC-13340, a new dihydropyridine, was studied in rats and compared with the action of nicardipine and other dihydropyridines. OPC-13340 showed more potent and longer hypotensive action than nicardipine when administered either intravenously (i.v.) or orally in normotensive and hypertensive rats. Among 6 compounds tested, (OPC-13340, nifedipine, nitrendipine, nisoldipine, nicardipine and diltiazem), OPC-13340 was the most potent and long-acting when administered orally to spontaneously hypertensive rats (SHR). Tachycardia after administration of OPC-13340 was less or diminished earlier than that of nicardipine. Oral administration of OPC-13340 (3 mg/kg) once daily for 13 days did not cause any rebound phenomena in SHR. The compound inhibited Ca- or K-induced contractions in isolated rat aorta and shortened action potential duration in guinea pig papillary muscle, suggesting Ca channel blocking action. OPC-13340 might be useful as a drug for once-daily therapy of essential hypertension.

Topics: Action Potentials; Animals; Antihypertensive Agents; Blood Pressure; Calcium; Calcium Channel Blockers; Dihydropyridines; Guinea Pigs; Heart Rate; Hypertension, Renovascular; In Vitro Techniques; Male; Muscle Contraction; Muscle, Smooth, Vascular; Papillary Muscles; Rats; Rats, Inbred SHR; Rats, Inbred Strains