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Blood Pressure Control -- Timing Matters

Some Drugs Work Better at Certain Times of the Day

By Salynn Boyles
WebMD Health News

Jan. 24, 2003 -- Timing may be more important than we thought when it comes to treating high blood pressure. A new study also lends support to the idea that high blood pressure is best controlled with a combination of drugs.

Researchers from the University of Melbourne found that some blood pressure medicines work best at certain times of the day. Some drugs did not lower blood pressure at all at night, while others medications worked best during this time.

Doctors often increase a single drug's dose to get blood pressure under control. But the researchers say that combining different types of blood pressure drugs -- rather than taking high doses of a single drug -- might be the better way to go. This sentiment was also expressed last month in a widely publicized study from the National Heart, Lung, and Blood Institute (NHLBI). Government researchers not only found that diuretics -- the oldest and cheapest blood pressure drugs -- work better than newer treatments, but that most patients need more than one type of medication to control their blood pressure effectively.

"It is becoming increasingly clear that a regimen of medications, which includes a diuretic, is a superior approach for most patients," Daniel Jones, MD, American Heart Association blood pressure spokesman, tells WebMD. "I think a lot will be written about combination therapy in the next few months, and you will see us increasingly trying to change the mindset of both the physician and patient who may be looking for one magic drug."

In the Australian study, reported in January's issue of the American Journal of Hypertension, researchers compared four of the most widely prescribed classes of blood pressure drugs -- diuretics, beta-blockers, calcium-channel blockers, and angiotensin converting enzyme (ACE) inhibitors.

Twenty-four people with high blood pressure over the age of 65 took each of the drugs and a placebo for two months each. Blood pressure measurements were repeatedly taken over 24 hours during each treatment period.

Researchers found that the diuretic and calcium-channel blocker were effective around the clock. The beta-blocker was the least effective of the four drugs overall and it had no effect on blood pressure during the night or in the early morning hours. ACE inhibitors actually worked best while the study participants were sleeping, but had little effect on blood pressure during the day.

Blood pressure during sleep may be an important contributor to damage to the heart and other organs, according to lead researcher Trefor O. Morgan, MBBS.

Jones tells WebMD that it is too soon to know whether the timing of treatment for high blood pressure is critical. But he agrees with the Australian study's conclusion that combining drugs may offer the best chance for blood pressure control. Jones is currently serving on an NHLBI steering committee updating blood pressure treatment guidelines. He says the revised guidelines will likely reflect this thinking.

"If one drug effectively gets blood pressure down to your goal then that one drug is all you need," he says. "Unfortunately, that is not what is happening with most patients."

Not sure which type of blood pressure medicine you're taking? Consult this list.