Take medicines at bedtime for better blood pressure control?

By Sophie Ramsey

BMJ Group News

What do we know already?

High blood pressure is extremely common, affecting 1 in 3 men and women in the UK. If left untreated, it can damage the walls of blood vessels, increasing the risk of heart attacks, strokes, kidney disease, and heart failure.

Although lifestyle changes (such as eating less salt, exercising, and losing weight) can lower blood pressure, many people also need to take medicines. Common blood pressure drugs include diuretics, ACE inhibitors, calcium channel blockers, and angiotensin II receptor blockers (ARBs). These can all work well, but some people continue to have high blood pressure despite treatment.

Researchers have wondered whether what time of day people take their medicines might affect how well these drugs work, as our blood pressure has natural variations throughout the day. For example, it is typically lower at night, and then rises after we wake. However, some people’s blood pressure stays too high at night, which has been linked to a raised risk of heart attacks and other serious problems. Might night-time dosing lead to better blood pressure control at night as well as throughout the day, and lower these risks?

A recent review of studies provides some support for this, finding that taking blood pressure drugs in the evening lowers people’s average blood pressure more than taking them in the morning. However, the researchers weren’t able to say whether this might lead to fewer serious problems, such as heart attacks, because studies hadn’t looked at this directly.

The new study took a closer look. Researchers recruited 661 people who had high blood pressure and chronic kidney disease - two conditions that are often related. The participants were randomly assigned either to take all their blood pressure medicines when they woke or to take at least one medicine at bedtime. The researchers then followed the people for up to eight years.

What does the new study say?

People who took at least one medicine at night had lower blood pressure while they slept and better blood pressure throughout the day. Of those taking medicines at night, 56 percent had good blood pressure control, compared with 45 percent of those taking their medicines in the morning.

People who took their medicines at bedtime were also less likely to have a heart attack or stroke, or die of heart or circulation problems during the study. The researchers found that, each year, 15 in 1,000 people who took their medicines in the morning would have one of these serious problems, compared with 5 in 1,000 of those who took one or more of their medicines at night.

How reliable is the research?

This was a large, good-quality study (a randomised controlled trial) that followed participants for several years, and its findings should be fairly reliable.

However, the study only included people who had chronic kidney disease as well as high blood pressure, so we can’t be certain these findings apply to people who have high blood pressure alone. The study also didn’t compare the types of blood pressure medicines people were taking. So we don’t know whether bedtime dosing would be more helpful for some medicines than others.