Phentolamine

Abstract

SUMMARYIn 6 patients with pulmonary edema, the intravenous administration of phentolamine at a rate of 0.3mg./min. resulted in a rapid alleviation of symptoms and signs.In one patient with severe left ventricular failure a complete hemodynamic study was possible and the infusion of phentolamine produced a striking improvement in the measured hemodynamic functions.Phentolamine may prove to be a valuable and effective drug for the treatment of patients in pulmonary edema due to left ventricular failure. Additional Indexing Words:Congestive heart failure Inotropic drug T AYLOR and his co-workers1)-3) have investigated the hemodynamic effects in man of the acute intravenous injection of 5mg. of phentolamine and of the intravenous infusion of phentolamine at a rate of 2mg./min. for 10min. Both methods of administration produced an increase in the heart rate and cardiac output and a decrease in the systemic arterial pressure and systemic vascular resistance. They postulated that the decrease in the peripheral resistance produced a reflex increase in the cardiac output. Evans, Smulyan, and Eich4) made a similar observation and came to a similar conclusion. Measurements of the force of contraction using a strain gauge arch, or of the speed of contraction employing the left ventricular dp/dt, were not, however, utilized by these workers. On the other hand, Goodman and Gilman5) state that phentolamine given intravenously produces vasodilatation and cardiac stimulation and that blood pressure response depends upon the relative contribution of these two effects. The vasodilatation is due primarily to a direct action on vascular smooth muscle, although, with higher doses, alpha adrenergic blockade may also be involved.

A comparison of the electrophysiological actions of phentolamine with those of some other antiarrhythmic drugs on tissues isolated from the rat heart

“…This has been considered by many to be a laboratory curiosity and the drug has been little utilized for therapeutic purposes, despite enthusiastic claims by several groups of cardiologists. Clinical experience with the drug has been reviewed by Gould & Reddy (1976). Interest in the antiarrhythmic action of phentolamine was revived recently, by reports that phentolamine, in company with certain other x-adrenoceptor antagonists, supresses ventricular tachyarrhythmias produced in experi-mental animals by coronary artery ligation and reperfusion (Sheridan, Penkoski & Sobel, 1980;Stewart, Burmeister, Burmeister & Lucchesi, 1980;Penny & Sheridan, 1982;Pogwizd, Sharma & Corr, 1982).…”