Blacks who have high blood pressure can lower it more effectively with drugs known as calcium channel blockers than with two other categories of medication, according to a new study from the University of Maryland Medical Center in Baltimore.

The study of 394 men and women, all of whom had mild to moderate high blood pressure, found that calcium channel blockers were significantly more effective than either atenolol, a beta blocker, or captopril, a class of medication known as angiotensin-converting enzyme inhibitor.

About 75 percent of patients who took the calcium channel blocker known as verapamil SR lowered their blood pressure, compared to 60 percent of those who took atenolol and 57 percent of those who were on captopril.

High blood pressure, which leads to an increased risk of stroke, kidney disease and premature heart disease, afflicts blacks disproportionately: 40 percent of blacks suffer from hypertension, compared to 20 percent of whites.

"Blacks are at much higher risk of serious complications from hypertension," said Elijah Saunders, a co-author of the study and director of the University of Maryland Medical Center's Division of Hypertension. The study will appear in the August issue of the Archives of Internal Medicine.

Previous studies have shown that some medications are less effective in controlling hypertension in blacks than in whites, because of differences in enzyme levels and variations in sensitivity to sodium.

A class of drugs known as diuretics has been most effective in treating high blood pressure in blacks, but because diuretics also raise blood cholesterol and lower blood potassium, their benefits may not always outweigh their risk.