Taking a blood pressure pill at bedtime instead of in the
morning might be healthier for some high-risk people.
New research suggests that simple switch may normalize patterns
of blood pressure in patients at extra risk from the twin epidemics
of heart and kidney disease.
Why? When it comes to blood pressure, you want to be a dipper.
In healthy people, blood pressure dips at night, by 10 to 20
percent. Scientists don't know why, but suspect the drop gives
arteries a little rest.
People with high blood pressure that doesn't dip at night -- the
non-dippers -- fare worse than other hypertension sufferers,
developing more serious heart disease. Moreover, heart and kidney
disease fuel each other -- and the 26 million Americans with
chronic kidney disease seem most prone to non-dipping. In addition
to heart problems, they're at extra risk of their kidney damage
worsening to the point of dialysis.
Most blood pressure patients need two or three medications. So
Italian researchers performed an easy test: They told 32
non-dippers with kidney disease to switch one of those drugs from a
morning to a bedtime dose. In two months, nearly 90 percent of
these high-risk patients had turned into dippers. Their nighttime
blood pressure dropped an average of 7 points, without side effects
or increase in daytime blood pressure.
Better, a key sign of kidney function improved significantly,
too, Dr. Roberto Minutolo of the Second University of Naples
reports this month in the American Journal of Kidney
Diseases.
It's the latest research in the field of chronotherapy: How our
bodies' internal rhythms make certain diseases worse at certain
times of the day, and in turn affect how to time treatments.
While the Italian study is too small for proof, similar studies
from Europe also back a bedtime switch for non-dippers. The work is
catching the attention of US hypertension specialists, and now
doctors at Baltimore's Johns Hopkins University are planning a
larger study to see if a bedtime switch really could give certain
people healthier hearts and kidneys.
How big a problem is non-dipping?
"I think it's huge," says Hopkins' Dr. Lawrence Appel. "This is
our best lead" into why black Americans with kidney disease, in
particular, tend to worsen despite treatment.
Appel found 80 percent of black kidney patients in a recent
study were non-dippers. Most startling, 40 percent had nighttime
blood pressure that was even higher than daytime levels.
Two-thirds of chronic kidney disease patients, and at least 10
percent 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. Most people get their blood pressure
checked only during the day. 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 the readings.
And most patients who take several once-a-day pills swallow them
all in the morning, meaning they all start wearing off around the
same time, says Dr. Gina Lundberg of St. Joseph's Hospital in
Atlanta.
"It does make good sense to take some in the morning and some in
the evening," says Lundberg, a spokeswoman for the American Heart
Association.
Everyone has an internal clock, determined by genes, that
affects health. Many of these biological rhythms are circadian,
meaning they fluctuate on a 24-hour cycle.
Consider how that can affect the timing of treatments. Some
older "statin" pills fight cholesterol best if taken at bedtime;
they target a liver enzyme that's most active at night. Asthma
attacks are more frequent at night, and the stomach secretes more
heartburn-causing acid at night, affecting some patients' dosing
requirements. Researchers even are studying how to better time
certain cancer chemotherapies and allergy treatments.
The best-known example: Blood pressure jumps in the early
morning hours, as the awakening body produces more stress hormones.
That's also why heart attacks and strokes are most common in the
morning.
The nighttime dipping problem has gotten far less attention. The
new Italian study marks an important advance, says Dr. Mahboob
Rahman of the University Hospitals of Cleveland.
"We know now that you can change medication timing and lower
blood pressure at night," he explains.
That doesn't mean everyone should switch willy-nilly to bedtime
dosing. Morning may be best for people on just one drug, and no one
yet knows if the switch truly gives non-dippers better overall
health. "That's the million-dollar question," Rahman cautions.
Still, Lundberg says it's worth asking your doctor how to time
doses, saying one at night for someone taking multiple medicines
couldn't hurt.
(Agencies via China Daily December 19, 2007)