Diuretics Still Work for Blood Pressure

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The old-fashioned medications known as “water pills” may be better for treating high blood pressure than newer, more expensive drugs, according to results from the largest hypertension clinical trial ever conducted.

New evidence shows diuretics, which rid the body of excess sodium and water, should be the first medication used when treating high blood pressure or used with other heart medication drugs prescribed for a particular patient.

“[This study] answers a question that has been around as long as I have been in the arena,” says Paul Whelton, M.D., M.Sc., a member of the study’s steering committee, senior vice president for health sciences and professor of epidemiology and medicine at Tulane University Health Sciences Center in New Orleans. “Any time I saw a patient, that was the question in my head: ‘What is the best medication to prescribe?'” says Whelton, a physician for 30 years.

“The point of this study is that it provides convincing evidence that diuretics are unsurpassed not only in helping to lower blood pressure but also in reducing cardiovascular events,” Whelton says.

This study, called the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT), was sponsored by the National Heart, Lung, and Blood Institute and is the first to put the newer medications head-to-head with older ones, which have been around for 40 years. Medications such as calcium channel blockers and ACE inhibitors emerged in the early 1980s.

Diuretics comprised 56 percent of all high blood pressure medications prescribed in 1982. That rate dropped to 27 percent in 1992. Had the pattern not changed prescription costs for that period would be have been $3.1 billion less, according to the study.

Diuretics cost roughly an average of $25 a year versus $600 with newer medications. About 24 million Americans take drugs to lower their blood pressure at an estimated cost of $15.5 billion a year.

Throughout an eight-year period, researchers in the ALLHAT study examined 42,418 people ages 55 and older at 623 sites in the United States, Canada, Puerto Rico and the U.S. Virgin Islands. The study looked at the ACE inhibitor lisinopril and the calcium channel blocker amlodipine compared with the generic diuretic chlorthalidone.

ACE inhibitors – angiotensin converting enzyme – interfere with the body’s production of angiotensin, a chemical that cause the arteries to constrict. The calcium blockers can reduce the heart rate and relax blood vessels.

The study, published in the Journal of the American Medical Association, found diuretics were better than calcium channel blockers in preventing heart failure and better than ACE inhibitors in preventing stroke, heart failure and chest pains.

Whelton says doctors and patients may have many reasons why they go with newer medications, including concerns that diuretics cause problems such as higher glucose and potassium levels. However, researchers in this study found these changes in the body did not result in a greater incidence of clinical complications or side effects than newer medications. The study showed 80 percent of people on the diuretic used in the study or similar drugs were still on it five years later, compared with amlodipine (80 percent) and lisinopril (73 percent). Also, Whelton speculates that some patients may have unwarranted fear of sexual side effects with the older medications.

The study also looked at the cholesterol-lowering drug called pravastatin compared with what doctors call the usual care – following a low-cholesterol diet. The drug reduced total cholesterol by 20 percent versus 11 percent among those following the low-cholesterol diet.

People ages 55 to 65, who do not suffer from hypertension run a 90 percent risk of developing it over the remaining years of their lives, according to the Framingham Heart Study. At least 50 million Americans older than age 5 – or one in every five Americans – have high blood pressure. And many may not be aware of this “silent killer” because there aren’t any symptoms for this life-threatening condition, which could lead to stroke and heart failure. And the American Heart Association says high blood pressure killed nearly 43,000 Americans in 1999, the most recent year reported.

External Resources

American Heart Association
 National Stroke Association
The National Heart, Lung, and Blood Institute
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