Results of the five-year study are published in Chronobiology International, an international journal on how biological rhythms affect the systems of living things. The authors say the findings will change the way high blood pressure medication is administered and have a profound impact on the type of treatment that hypertension patients receive.
In two articles, Chronobiology International covers and interprets the newly completed MAPEC study, which shows that the simple shift to taking medication at night instead of in the morning significantly increases efficacy in keeping blood pressure within a healthy range. In addition, taking medication at night offers extra protection against heart attacks, strokes and other types of cardiovascular diseases.
The results are impressive. The group of patients who took at least one of their medications at night experienced just one-third of the number of cardiovascular disease (CVD) episodes experienced by the group of patients who took all their medications in the morning.
"This study proves that the time of day when patients take their high blood pressure medications can make a huge difference due to the effect of the body's circadian rhythms on the actions of medications and because of the importance of preserving the normal day-night pattern of blood pressure in hypertension," explains the lead investigator of the MAPEC Study Professor RamÃ³n C. Hermida, PhD, Director of Bioengineering and Chronobiology Labs at the University of Vigo in Spain. "Conventional treatment typically advises taking blood pressure medications in the morning. The MAPEC study shows that conventional treatment is not the most effective way to help patients with high blood pressure."
Taking at least one blood pressure medication at bedtime - as opposed to taking all medications in the morning - was found, based on around-the-clock ambulatory blood pressure monitoring, to best normalize the sleep-time blood pressure. This is known to be the most sensitive predictor of a patient's 5-year risk of CVD mortality. In addition, the MAPEC study shows that taking medication at night is the best way to control daytime BP levels.
The study also highlighted the importance of knowing a patient's sleep-time blood pressure readings. While most hypertension patients can attest to the fact that their BP reading is normally taken during a daytime clinic, not knowing what a patient's blood pressure is doing over the entire 24-hour period - and crucially, what the sleep-time readings register - is like playing Russian roulette.
"Historically, medical professionals have operated on the assumption that sleep-time blood pressure levels will drop by 10-20 percent from daytime levels. However, for many patients - called non-dippers - this doesn't happen and sleep-time therefore becomes a high risk period," says Dr. Francesco Portaluppi of the Hypertension Center at the University Hospital of Ferrara in Italy and lead author of the perspectives article on the MAPEC study.
70 million people
More than 70 million people in the U.S. have hypertension. Millions suffer heart attacks and strokes every year. Imagine if those CVD episodes could be cut by almost two thirds. Professor Hermida and his team are convinced there is no time to lose.
"This study was the first to conclusively find that the time of day when medications are ingested not only affects efficacy but also CVD risk and these findings must fundamentally change the way patients are treated worldwide," said Portaluppi.
Experts who analyzed the study results conclude that a number of steps should be taken urgently in order to best utilize the findings and save lives.
First, 24-hour ambulatory blood pressure monitoring should be the proper means of differentiating the needs of BP patients and the only means of categorizing patients as non-dippers in the 24-hour pattern. It is also the best means of confirming that treatment goals of BP control are met, which include ensuring that sleep-time BP levels are in the correct range.
Second, elevated sleep-time blood pressure should be made an important new therapeutic clinical target for medications. Based on this and borne out by the results of the study, prescribing that hypertension medications be taken at night offers an inexpensive and highly efficacious means of controlling blood pressure without the need to increase either the dose or number of medications.
"Our body clocks are extremely powerful biological tools and this study offers insight and hard facts on how we can harness that power to help millions of people stay healthier and safer by ensuring that their blood pressure medications are taken as effectively as possible," said Dr. Michael Smolensky, Editor of Chronobiology International.