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Doxazosin Dropped from Major Antihypertensive Study

Cheryl A. Thompson

Citing poor results, the National Heart, Lung, and Blood Institute (NHLBI) has removed doxazosin from a major trial investigating the effectiveness of various classes of antihypertensive agents to prevent adverse effects from coronary heart disease (CHD). NHLBI advises patients who use an alpha1-adrenergic receptor blocker as treatment for hypertension to consult with their physician about a possible alternative therapy.

The Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack Trial, or ALLHAT, started in 1994 with four once-daily drug regimens for lowering high blood pressure:

• Amlodipine, a calcium-channel blocker, 2.5 to 10 mg/day,

• Chlorthalidone, a diuretic, 12.5 to 25 mg/day,

• Doxazosin, an alpha1-adrenergic receptor blocker, 2 to 8 mg/day, and

• Lisinopril, an angiotensin-converting-enzyme inhibitor, 10 to 40 mg/day.

When they started the study, the 42,448 patients were 55 years of age or older, had systolic or diastolic hypertension, and had at least one more risk factor for CHD, such as diabetes mellitus. About one fourth of these hypertensive patients also started a lipid-lowering treatment.

Investigators set out primarily to determine whether amlodipine, doxazosin, or lisinopril therapy would result in a lower incidence of deaths and nonfatal myocardial infarctions than chlorthalidone therapy. But an interim review of the data showed that, compared with the chlorthalidone group, the doxazosin group had 25 percent more cardiovascular events and twice the likelihood of being admitted to the hospital because of congestive heart failure.

ALLHAT is sponsored by NHLBI, in conjunction with the Department of Veterans Affairs and with support from pharmaceutical companies including Pfizer, manufacturer of doxazosin and amlodipine products.