One common type of blood pressure drug may not work as well as others at preventing heart death, a new study shows.

The data comes from women aged 50-79 enrolled in the Women's Health Initiative (WHI). It's the same study that showed hormone replacement therapy (search) to be less effective and more risky than previously thought. Now the study shows a higher risk of heart death in women who take blood pressure drugs known as calcium channel blockers (search).

Calcium channel blockers include, but are not limited to, drugs sold under the brand names Norvasc, Plendil, DynaCirc, Cardene, Procardia XL, Adalat, Cardizem, Dilacor, Tiazac, Diltia XL, Isoptin, Calan, Verelan, and Covera-HS.

Researcher Sylvia Wassertheil-Smoller, PhD, heads the epidemiology division at Albert Einstein College of Medicine, in Bronx, N.Y. The findings appear in the Dec. 15 issue of The Journal of the American Medical Association.

"We found that [high-blood-pressure] therapy combinations that contain the calcium channel blockers were associated with a higher risk of death from heart disease than were other combinations," Wassertheil-Smoller tells WebMD. "Doctors should be cautious with prescribing any drugs, but particularly with this one. Doctors may have a very good reason for giving a patient a calcium channel blocker, but it should not blindly be given."

Don't Stop Taking Blood Pressure Drugs

Should people stop taking these drugs? No, Wassertheil-Smoller says. Why not? It's dangerous to stop taking any prescribed medicine — blood pressure drugs in particular — before seeing one's doctor.

Current treatment guidelines say that all approved blood pressure drugs are safe and effective. The new findings do not change those recommendations, says American Heart Association spokesman Daniel Jones, MD, dean of the University of Mississippi School of Medicine.

"The bulk of clinical trials show calcium channel blockers are safe and effective at lowering blood pressure," Jones tells WebMD. "Our current guidelines focus on lowering blood pressure and not much on what class of drugs you use to do that. This study, while intriguing, doesn't do anything to change that."

Twofold Higher Death Risk

The study looked at more than 30,000 women with high blood pressure but no history of heart disease. Some of the women took only one kind of blood pressure drug:

—A diuretic or water pill. The most common water pill is hydrochlorothiazide

—A beta-blocker. Common brand names include Inderal, Tenormin, Lopressor, and Toprol-XL.

—An ACE inhibitor. Common brand names include Capoten, Vasotec, Prinivil, Zestril, Lotensin, Monopril, Altace, and Accupril.

—A calcium channel blocker. This includes drugs such as Norvasc, Cardizem, Calan, and Adalat.

Some of the women took combinations of these drugs.

A recent clinical trial showed that diuretics (search) are the best blood pressure drugs to try first. Among women in the WHI, there was no significant difference in heart deaths between women who took diuretics alone and women who took either beta-blockers (search) or ACE inhibitors (search). But those who took calcium channel blockers alone had a 55 percent higher risk of dying from heart disease.

When one blood pressure drug isn't enough, doctors often recommend combination therapy. In the WHI, the women who took a diuretic plus a calcium channel blocker had an 85 percent higher risk of death from heart disease than women who took a diuretic plus a beta-blocker. For women without diabetes, the risk of death was more than twice as high for those taking a diuretic plus a calcium channel blocker than for those taking a diuretic plus a beta-blocker.

These risks were seen in women with no existing heart disease. Doctors often prescribe calcium channel blockers for people with angina — heart-related chest pain — high blood pressure or some types of heart rhythm abnormalities. Wassertheil-Smoller stresses the need for patients to understand why their doctors recommend one drug and not another.

"The bottom line is one needs to consider why your doctor has recommended this particular combination of blood pressure drugs that you are on," she says. "Nowadays the public is very well informed about what therapy they are on. Part of being well informed is to talk with your doctor about the rationale for being on one therapy instead of another."

By Daniel J. DeNoon, reviewed by Brunilda Nazario, MD

SOURCES: Wassertheil-Smoller, S. The Journal of the American Medical Association, Dec. 15, 2004; vol 292: pp 2849-2859. Sylvia Wassertheil-Smoller, PhD, professor, epidemiology and population health, and head, division of epidemiology, Albert Einstein College of Medicine, Bronx, N.Y. Daniel Jones, MD, dean, University of Mississippi School of Medicine; and spokesman, American Heart Association.