CARDIOVASCULAR EFFECTS OF IMIPRAMINE

¹ Geigy Research Laboratories, Ardsley, New York

Imipramine possesses the following cardiovascular effects: It lowers the blood pressure in anesthetized dogs in doses from 1 to 8 mg/kg, i.v. However, in unanesthetized renal hypertensive dogs, single i.v. injections (0.32 to 3 mg/kg) of imipramine do not exert an antihypertensive effect. Myocardial contractility and heart rate are increased by low doses (320 µg, i.v.) and decreased by higher doses (2 to 5 mg/kg, i.v.) of imipramine. Coronary blood flow is increased after i.a. injection of small doses (5 to 10 µg), not changed after i.v. doses of 100 to 320 µg/kg, and decreased after i.v. administration of 2 to 5 mg/kg. In the isolated feline heart single doses of 10 to 300 µg cause a negative inotropic effect and increase coronary flow. Cardiac output in dogs is diminished after i.v. injection of 5 mg/kg. The carotid occlusion reflex, Bezold-Jarisch reflex and orthostatic hypertensive reflex are diminished by imipramine in doses up to 5 mg/kg, i.v. The vasopressor responses due to stimulation of the central end of the cut vagi, raising intracranial pressure and stimulation of the splanchnic nerve are unaltered, or, as in the case of the two latter procedures, sometimes enhanced.