Health
Timing is everything, even with pills
May 10, 2011
Nancy J. White
LIVING REPORTER
The time of day that you take your blood pressure medicine may determine how effective it is, according to a new study.
While many heart patients tend to pop their pills in the morning, researchers at the University of Guelph found that mice with high blood pressure had significantly improved heart structure and function when given an angiotensin-converting enzyme (ACE) inhibitor before sleep time.
ACE inhibitors are a class of drugs widely prescribed for patients with high blood pressure or after a heart attack or to treat congestive heart failure. Some commonly prescribed ACE-inhibitors include ramipril and enalapril.
In heart disease, the angiotensin system, the hormones targeted by ACE-inhibitor drugs, has a daily rhythm. It increases during sleep and can cause the heart to enlarge, explains researcher Tami Martino, lead author of the study to be published next week in the Journal of the American College of Cardiology.
“By targeting the hormones when they are at their highest, you decrease their levels so they don’t do as much damage to the heart,” explains Martino, as assistant professor of biomedical science at Guelph.
“The effect of taking the pill at wake-up was very similar to taking no drug at all,” she says. “It was very dramatic.”
While most people’s blood pressure dips at night, a large percentage of those with high blood pressure don’t experience that normal reduction, leaving them more susceptible to organ damage.
Heart cells replenish themselves during sleep, explains Martino. “We think about the brain and the importance of sleep, but it’s important for all organs, including the heart.”
Dr. Michael Sole, a cardiologist at the Peter Munk Cardiac Centre at Toronto General Hospital, is also an author of the study. He says that when he gets patients who take blood pressure medicine in the morning, he switches them to nighttime when the repair process takes place.
This study contributes to the growing field of chronotherapy, the timing of disease treatment to take advantage of daily physiological and molecular rhythms. By taking a drug at the right time of day, a patient may be able to increase its effectiveness and decrease toxicity and side effects.
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