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Published on February 25, 2020

Should you take your BP medicine at a different time of day?

BP Medicine Timing

People who have been diagnosed with hypertension usually take their blood pressure medicine in the morning when they first wake up. For most people, blood pressure and heart rate are higher in the morning and lower at night while they sleep. With that in mind, it makes sense to take the medication at the time of day when the blood pressure and heart rate are higher.

A large new study done in Spain turns that advice on its head. The Hygia Chronotherapy Trial published in the European Heart Journal included 19,168 patients ages 60 or older. Half of them were asked to take all of their blood pressure medications in the morning when they first woke up. The other half were instructed to take all their blood pressure medications at night, just before bed.

After a six-year follow-up, the results showed that those who took their medications at night had better controlled blood pressure and a 45 percent decreased risk of death or illness due to heart-related problems.

In the study, those who took their medications at bedtime reduced the risk of:

  • Stroke by 49 percent,
  • Heart attack by 44 percent,
  • Heart failure by 42 percent,
  • Coronary revascularization by 40 percent.

As promising as that sounds, cardiologist Lawrence McAuliffe, MD, at Cape Cod Healthcare’s Cardiovascular Center in Hyannis was cautious about interpreting the results in a simplistic fashion. The study results did not convince him to advise all of his patients to take their medications at night.

“It is certainly intriguing and it’s hard to argue with the impressive nature of their findings,” he said. “But like anything, it’s not as simple as one observation and one recommendation.”

His first concern with the study is that it was done entirely on one specific population: Caucasian Spaniards. There’s a rare chance that the protection those patients saw was from some kind of genetic predisposition. But that isn’t likely.

“If it works for this particular group of patients it ought to be transferable and effective to other groups of patients,” Dr. McAuliffe said. “That would become the nexus for a bigger study where you have a truly blinded and placebo-controlled study. You need to be sure that you are not introducing bias by your grouping of subjects. It would be interesting to see more studies done.”

Intuitively, the findings of the study might apply to certain patients like those with sleep apnea or diabetes, he said, because in that population of patients, blood pressure tends to be high at night. But Dr. McAuliffe cautioned against taking a blanket approach on this topic. Each patient is different, and each medication works in a different way to lower blood pressure, he said.

Not for Certain Patients

With some medications, it just wouldn’t make sense to move medications to bedtime, depending on the mechanism that makes them work and their half-life for how long they remain effective in the body. Diuretics are a perfect example of the mechanism issue.

“One of the effects of a diuretic is you urinate and get rid of fluid,” he said. “Do you want to give all your patients a diuretic at ten o’clock at night so that four hours later they have to get up and go to the bathroom? Sleep is restorative, so anything that interrupts that pattern can have a deleterious effect that may counterbalance any beneficial effect.”

Another category of medicines that you would not want to take at night are beta blockers, Dr. McAuliffe said. In addition to helping control blood pressure, these drugs reduce heart rate. Since the heart rate automatically goes down at night, taking the medicine in the morning offers the heart rate response which helps control blood pressure during the day, when it is more helpful.

A lot of patients take more than one blood pressure medication. In many instances, doctors prefer to prescribe a low dose of a couple of drugs rather than a high dose of one drug, to minimize the risk of side effects. Since it is very common for patients to take all their blood pressure medications at the same time in the morning, sometimes they all hit at once and the patient feels poorly in the late morning, Dr. McAuliffe said.

In those cases, he sometimes tells people to take their medications at different times of the day, depending on what the medications actually do. For example, for a busy person who has a lot of errands or appointments in the morning, taking their diuretic in the late afternoon when they are home for the day could be preferable to constantly searching for a public restroom.

Other medications would be fine to take at night, if you are having negative symptoms in the morning, Dr. McAuliffe said. Calcium channel blockers, like the commonly prescribed drug amlodipine, work by diluting the arteries to reduce the pressure there. This makes it easier for the heart to pump blood and reduces the heart’s need for oxygen.

Since it doesn’t make you urinate and it doesn’t affect heart rate, that is a medication that could be given at night because its half-life is such that the patient’s blood pressure would be fine in the morning, he said. Other calcium channel blockers and the class of medications known as ARBs are also safe to take at night, he added.

Looking for the Sweet Spot

One of the biggest drawbacks to spreading medicines out over the day is there is a chance of noncompliance because people might forget to take the dose at the correct time. Plus, if you forget to take a morning dose, you might remember an hour or two later. If you forget to take a nighttime dose, you won’t be aware of your mistake until you wake up seven or eight hours later.

“We’re looking for the sweet spot of convenience and compliance,” Dr. McAuliffe said. “We don’t want patients to miss medications and not take them because it’s inconvenient, and we don’t want them to not take it because of side effects that are disturbing. But we also want to deliver an effective treatment regiment, so I’ll often find myself, with these patients, spreading out their medications during the day.”

Dr. McAuliffe advises people who currently take blood pressure medications in the morning to talk with their doctor before deciding to take their pills at night.