Blood pressure medication effectiveness can be influenced by the time of day the pills are taken. New research suggests that a simple switch in timing may normalize patterns of blood pressure in patients at extra risk from heart and kidney disease. Heart and kidney disease fuel each other and, in addition to heart problems, kidney patients are at extra risk of their kidney damage worsening to the point of dialysis.
When it comes to blood pressure, you want to be a dipper. In healthy people, blood pressure dips at night, by 10-20%. Scientists aren’t sure why, but suspect the nightly drop gives arteries a rest. Those with high blood pressure that doesn’t dip at night—non-dippers—fare worse than other hypertension sufferers and tend to develop more serious heart disease; 26 million Americans with chronic kidney disease seem most prone to non-dipping.
Because most blood pressure patients need a few medications daily, in a study in Italy, researchers had 32 non-dippers with kidney disease switch one drug from a morning to a bedtime dose. In two months, nearly 90 percent of these high-risk patients became dippers, their nighttime blood pressure dropping an average of seven points without side effects or increase in daytime blood pressure and with kidney function improvement. The study is too small for proof but similar studies from Europe back the results, the work is catching the attention of U.S. hypertension specialists, and Baltimore’s Johns Hopkins University is planning a larger study.
This represents the latest research in chronotherapy—how our internal rhythms make some diseases worse at certain times of the day, affecting how to time treatments. Many biological rhythms are circadian—fluctuating on a 24-hour cycle. Most people’s blood pressure is checked during the day and a 24-hour blood pressure monitor can tell but is rarely used, partly because insurance seldom pays for the extra visit to download and diagnose readings. Generally, patients who take several once-a-day pills swallow them in the morning, so they all start wearing off around the same time. Some older statins fight cholesterol best if taken at bedtime, targeting a liver enzyme that’s most active at night. Asthma attacks are more frequent at night; the stomach secretes more heartburn-causing acid at night; and blood pressure jumps in the morning when the body produces more stress hormones, which is why heart attacks and strokes generally occur then. Researchers are studying how to better time certain cancer chemotherapies and allergy treatments.
According to Hopkins’ Dr. Lawrence Appel, “This is our best lead” into why black Americans with kidney disease, tend to worsen despite treatment. Appel found 80% of black kidney patients were non-dippers and 40% had nighttime blood pressure higher than daytime levels. Two-thirds of chronic kidney disease patients, and at least 10% of the general population, are estimated to be non-dippers, says Dr. Joseph Vassalotti of the National Kidney Foundation. One theory is that their bodies have trouble excreting salt, yet few patients have ever heard of the problem and few doctors know who is affected.
This doesn’t mean people should switch to bedtime dosing; but it’s worth asking your doctor how to time doses.
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