Drug Profile

The alpha-blocker family includes alfuzosin (UROXATRAL), doxazosin (CARDURA), prazosin (MINIPRESS), tamsulosin (FLOMAX), and terazosin (HYTRIN). Three of these drugs, doxazosin, prazosin, and terazosin, are approved by the FDA to treat high blood pressure. Alfuzosin and tamsulosin are FDA-approved to treat benign prostatic hyperplasia (BPH), or an enlarged prostate gland. Terazosin and doxazosin are approved for both high blood pressure and enlarged prostate.

The National Heart, Lung, and Blood Institute, a part of the National Institutes of Health, announced in early March 2000 that it had stopped one part of a large high blood pressure study because one of the drugs being tested, the alpha-blocker doxazosin, was found less effective than the old water pill (diuretic) chlorthalidone (HYGROTON) in reducing some forms of cardiovascular disease.[1]

The study, called the Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack Trial (or ALLHAT for short), found that users of doxazosin had 25 percent more cardiovascular events and were twice as likely to be hospitalized for congestive heart failure as users of the thiazide diuretic chlorthalidone. The drugs were similarly effective in preventing heart attacks and in reducing the risk of death from all causes. The doxazosin group also had poorer compliance with treatment—only 75 percent were still on the drug or another alpha-blocker after four years, compared with 86 percent still taking chlorthalidone or another diuretic.

Overall, chlorthalidone was found to be superior to doxazosin for blood pressure control, drug compliance, and in reducing cardiovascular complications. In addition, chlorthalidone is much less expensive than doxazosin.

In light of the ALLHAT results, the American College of Cardiology recommended on March 15, 2000, that physicians reassess the use of alpha-blockers for the treatment of high blood pressure.

If you have high blood pressure, the best way to reduce or eliminate your need for medication is by improving your diet, losing weight, exercising, and decreasing your salt and alcohol intake. Mild hypertension can be controlled by proper nutrition and exercise. If these measures do not lower your blood pressure enough and you need medication, hydrochlorothiazide (ESIDRIX, HYDRODIURIL, MICROZIDE) or chlorthalidone (HYGROTON), water pills, should be used first, starting with a low dose. These drugs also cost much less than other blood pressure drugs.

There is growing evidence that thiazide diuretics, such as hydrochlorothiazide, significantly decrease the rate of bone mineral loss in both men and women because they reduce the amount of calcium lost in the urine.[2] Research now suggests that thiazide diuretics may protect against hip fracture.[3] 

If your high blood pressure is more severe, and hydrochlorothiazide alone does not control it, another family of high-blood-pressure-lowering drugs may be added to your treatment. In this case, your doctor would prescribe the hydrochlorothiazide and the second drug separately, with the dose of each drug adjusted to meet your needs, rather than using a product that combines the drug in a fixed combination. 

Whatever drugs you take for high blood pressure, once your blood pressure has been normal for a year or more, a cautious decrease in dose and renewed attention to nondrug treatment may be worth trying, according to The Medical Letter.[4]

An editorial in the British Medical Journal stated:

Treatment of hypertension is part of preventive medicine and like all preventive strategies, its progress should be regularly reviewed by whoever initiates it. Many problems could be avoided by not starting antihypertensive treatment "until after prolonged observation. ...Patients should no longer" be told that treatment is necessarily for life: the possibility of reducing or stopping treatment should be mentioned at the outset.

Intraoperative Floppy Iris Syndrome (IFIS) has been observed during cataract surgery in some patients currently taking or previously treated with alpha blockers. If you are having cataract surgery and are taking or have taken an alpha blocker, be sure to alert the operating physician.[5],[6]

MEDSAFE (an agency in New Zealand similar to the FDA) issued an advisory in April 2014 that the Center for Adverse Reaction Monitoring had received seven reports of nightmares associated with doxazosin therapy since 1992.[7]