Phentolamine.

The clinical uses of phentolamine have widened since its introduction as an anti-hypertensive agent. The vasodilating action of the drug as well as its postive inotropic effects have led to its use in treating congestive heart failure. Recently, phentolamine has been use by several groups to improve left ventricular function in acute myocardial infarction. There appears to be great promise for the use of phentolamine in this clinical setting. The drug given intravenously or orally can suppress ventricular premature beats and supraventricular premature beats. However, the experience of phentolamine as an antiarrhythmic agent is still limited. Similarly, the relief of angina pectoris by phentolamine requires confirmation by additional clinical studies. Phentolamine can be used as a provocative test in idiopathic hypertrophic subaortic stenosis. Since it does not produce cardiac arrhythmias, it may be safer than isoproterenol. The comparative effectiveness of phentolamine and isoproterenol in diagnosing I.H.S.S. is unknown. Phentolamine has been advocated for several years as a beneficial agent for the treatment of shock. The experience is still limited to a few groups who have reported favorable results. Phentolamine has been used as a bronchodilator and a pulmonary artery dilator. The preliminary reports appear favorable. However, continused investigation is warranted. A sensitive measurement of the blood levels of phentolamine is not available. When this is accomplished, further insight into the metabolism of this drug will be forthcoming.