Angiotensin-converting enzyme (ACE) inhibitors , drugs taken for high blood pressure and post-heart attack work best only when taken at night, report researchers from Canada.
Tami Martino, an assistant professor in biomedical sciences at the University of Guelph and one of the study's author states that these drugs are given in the morning for the sake of convenience.
A hormone that makes blood vessels tighten and consequently, the heart to work harder to pump blood through the body, leads to cardiac hypertrophy, the thickening of the heart. This hormone is the most active at night, and so, taking the body's biological rhythm into account, the ACE inhibitors need to be administered at night.
Captopril, a short-acting version of the drug was tried out on mice with high blood pressure. After the mice were dosed either at sleep time or wake time for eight weeks, the researchers studied the effect of timing. The difference was remarkable, for the mice who had taken the drug at night had healthier hearts comparable to those that had no heart disease, whereas, the others who had the drug administered in the morning showed no noteworthy change; in fact, the drug could have been a placebo for all the effect it had.
Although this study was done only on mice, researchers from Spain had, in an earlier study, backed up these new findings by involving more than 21,000 men and women with high blood pressure and found the same result, that those who took at least one of their blood pressure medications at night had fewer heart attacks and strokes than patients who took all their pills in the morning.
Martino says that the cardiovascular system has its own unique kind of rhythm. Heart rate and blood pressure rise by day and dip at night and so medication needs to be given at night for maximum benefit.
This study proves "for the first time that if you give (ACE inhibitors) at the right time, it really has a dramatic effect on heart structure and function... you're showing that if you time it to when the body is physiologically most receptive to it that you can actually produce more benefit."
Chronotherapy, the timing of drug administration to maximize benefits and minimize harm, has stimulated research. Studies are now being carried out whether, as in cardiovascular diseases, timing chemotherapy treatment would benefit cancer patients.