Minoxidil: An Underused Vasodilator for Resistant or Severe Hypertension

Domenic A. Sica, MD

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In This Article

Abstract and Introduction

Minoxidil is a direct vasodilator introduced in the early 1970s for the treatment of hypertension. It is capable of reducing blood pressure in most persons with resistant hypertension where therapy has failed with multidrug regimens. Minoxidil's effect can be limited because of an increase in pulse rate and/or sodium (and water) retention. The latter may prove quite debilitating in some patients. Thus, minoxidil is generally administered with both a diuretic and an agent that can keep pulse rate in check, such as a ß blocker or a combined -ß blocker. The prominent tachycardia with minoxidil can aggravate myocardial ischemia and, if long-standing, leads to left ventricular hypertrophy. Minoxidil has a particularly annoying side effect of hypertrichosis that may limit its use, particularly among women. Minoxidil use is infrequently associated with the idiosyncratic onset of a pericardial effusion. If a patient's hypertension is severe enough to warrant minoxidil therapy, a hypertension specialist should probably become involved in the patient's care. The use of this medication should be limited in view of the availability of effective agents with fewer side effects. There is, however, a place for minoxidil in the treatment of resistant hypertension especially in patients with advanced renal disease.

Direct vasodilator drugs, such as hydralazine and minoxidil, are generally held in reserve for patients with advanced stage 2 hypertension who have not responded to conventional multidrug antihypertensive regimens.[1,2] Although these compounds are typically reserved for resistant hypertension, they are well suited for patients with accelerated hypertension. In addition, there are circumstances in which they can be employed in less severe cases. For example, hydralazine in a dose of 25-100 mg twice daily was a Step 3 medication in The Antihypertensive and Lipid-Lowering to Prevent Heart Attack Trial (ALLHAT), albeit on a per protocol basis. The rationale for the use of hydralazine in this trial related to its direct vasodilatory mode of action being different and complementary to the other drug classes in use.

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