News - Hypertension Week of Jan. 26, 2003/ Vol. 2 No. 04

Study: Hypertension Drug Benefit Depends on Time of Day

The effectiveness of different classes of hypertension drugs depends on the time of the day they are taken and treatment strategies should be considered accordingly, according to a study reported in the January issue of the American Journal of Hypertension.

"This study recognizes the growing importance of time of day when a person should take his or her hypertension medication to achieve the drug's maximum effect," said Dr. Michael A. Weber, an editor of the American Journal of Hypertension. "Timed administration of medication is going to play a greater role in treating hypertension since blood pressure rises and falls throughout the day."

"Blood pressure is controlled by a large number of variables," concluded researchers from the University of Melbourne in Australia. "We recognize this by the individual variation that occurs in response to specific drugs. The evidence from this study that different drugs work more effectively at different times of the day may require us to rethink our therapeutic strategies."

Researchers found that hydrochlorothiazide diuretics and the calcium channel blocker felodopine were more consistent over 24-hours than the beta-blocker atenolol and the angiotensin converting enzyme (ACE) inhibitor perindopril.

The study involved 24 patients over the age 65 with untreated systolic hypertension. Each
patient received four different treatments and a placebo for eight weeks and wore an ambulatory blood pressure monitor to record blood pressure during the day and at night.

The researchers found that ACE inhibitors caused a larger fall in blood pressure while patients slept than when they were awake, while beta blocking drugs had a smaller and insignificant effect during sleep. The diuretic and the calcium channel blocker appeared to have a relatively consistent effect on blood pressure.

"The responses to atenolol (beta blocker) and perindopril (ACE inhibitor) were highly dependent on the time of day," the researchers said. "The greater effectiveness of ACE inhibitors at night may explain in part their greater effectiveness at reducing cardiac hypertrophy and coronary artery deaths."

American Journal of Hypertension: January 2003; 16:46-50