Unusual cases of resistance to minoxidil therapy

Minoxidil was used to treat 112 patients with severe and refractory hypertension during a period of 8 years. The drug was highly effective and resistant cases were distinctly unusual. We reported here 4 such cases. In 2, the patients showed no response to large doses, even when minoxidil was combined with other drugs. In the third, a patient with severe gastrointestinal abnormalities could not retain the drug. No proof exists that if it had been given parenterally it would not have been effective. The last case is of a patient with obstructive cardiomyopathy (IHSS) who reponded well to minoxidil. Because of the vasodilator's profound effect on the cardiovascular system, changes in this patient's hemodynamics occurred which made fluid retention and cardiomegaly intolerable. Patients with severe obstructive cardiomyopathy should be considered for therapy with a strong vasodilator only with caution and with the awareness that fluid retention may be disproportionately large.