Sustained effectiveness of minoxidil in heart failure after development of tolerance to other vasodilator drugs.

Although a variety of vasodilator drugs produce acute hemodynamic improvement in patients with severe chronic heart failure, long-term treatment with these agents may be associated with the development of drug tolerance and loss of initial beneficial effects. Five serial right heart catheterizations in a 78 year old man with severe chronic heart failure due to idiopathic cardiomyopathy documented the development of hemodynamic and clinical tolerance to oral hydralazine and oral captopril after initial responses were observed to both agents. However, sustained hemodynamic and clinical improvement by invasive testing was noted with minoxidil (20 mg orally twice daily) after 4 and 9 weeks of continuous therapy. These observations indicate that pharmacologic tolerance may occur with a variety of vasodilator drugs and may account for the failure of some patients to improve clinically with long-term therapy despite initial favorable hemodynamic effects. However, such tolerance seems to be drug-specific and, hence, its recognition in an individual patient does not prelude responsiveness to other vasodilator agents.