There are several classes of drugs for lowering high blood pressure, but the best type to begin with is one of the oldest and cheapest: a ‘water pill’ or diuretic, researchers say.

Results of a big study called ALLHAT (standing for Antihypertensive and Lipid-Lowering Treatment to Prevent Heart attack Trial) show that the diuretic chlorthalidone is as good as an ACE inhibitor (lisinopril) or a calcium channel blocker (amlodipine) in preventing major heart or kidney complications resulting from high blood pressure. Chlorthalidone actually comes out ahead in its ability to prevent heart failure.

Based on the findings, Dr. Jackson T. Wright, at Case Western Reserve University in Cleveland, and his associates advise that diuretics should be considered the drug of choice for initial therapy of hypertension for both blacks and non-blacks.

As reported in this week’s Journal of the American Medical Association, ALLHAT included 33,357 patients with high blood pressure, 35 percent of whom were black; they were 55 years of age or older with at least one other risk factor for Heart disease.

The subjects were randomly assigned to treatment with chlorthalidone, amlodipine or lisinopril. Other drugs were added as need to attain a blood pressure of 140-over-90 or lower.

After an average follow-up of nearly five years, Wright’s group found no significant differences among the treatment groups in the rates of heart attack or fatal coronary heart disease among blacks or non-blacks.

However, for those on the calcium blocker, the risk of heart failure was 46 percent higher in blacks and 32 percent higher in non-blacks than among those treated with the diuretic.

For those treated with the ACE inhibitor, compared with the diuretic, the risk of Stroke  was 40% higher for blacks but not non-blacks. The risk of heart failure was raised for both subgroups.

The authors of the analysis point out that “ALLHAT is the first large-scale trial with a substantial number of black participants” aimed at evaluating different blood pressure treatments.

SOURCE: Journal of the American Medical Association, April 6, 2005.