Blood pressure drugs work far better if taken at night, study shows

https://www.theguardian.com/society/2019/oct/23/blood-pressure-drugs-work-far-better-if-taken-at-night-study-shows

Blood pressure drugs work far better if taken at night, study shows

Nicola Davis

Wed 23 Oct 2019 00.05 BST

Taking blood pressure medication at bedtime rather than on waking halves the risk of events such as heart attack and stroke, a major study has revealed. Experts say the findings could potentially transform the way such medications are prescribed, but questions remain, not least why taking the medication at night has such a profound effect.

Prof Ramón Hermida, first author of the study from the University of Vigo in Spain, said the effect was thought to be down to the body’s internal clock that means processes and chemicals within our bodies vary over a 24-hour period. The upshot, he said, was that the same drug could have vastly different effects if taken at a different point in time, something that has been dubbed “chronotherapy”.
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Writing in the European Heart Journal, the team report how they randomly split more than 19,000 adults with high blood pressure into two groups. Half of the patients were asked to take all their medication at bedtime while the other half were asked to take it upon waking.

Crucially, said Hermida, fixed times were not given so that participants took their medication at the same point in the daily routine.

The patients were then followed for between four and eight years, with blood pressure measured over a 48-hour period at the outset and at least once a year during the study. In total 1,752 cardiovascular events such as heart attack, stroke, death from cardiovascular disease and heart failure were recorded during the study.

While the impact on daytime blood pressure was similar, those taking their medication at bedtime had a small but significantly greater reduction in blood pressure during sleep compared with those taking medication on waking, as well as a greater difference in blood pressure when sleeping compared with being awake.
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After taking into account factors such as age, sex, smoking status, history of cardiovascular events and typical decrease in blood pressure when asleep, the team found patients who took their medication at bedtime had a 56% lower risk of death from cardiovascular disease, a 49% lower risk of stroke and a 44% lower risk of heart attack compared with the other group.

The team say the findings need to be confirmed in a more diverse range of ethnicities, while it is not clear if they would hold among those undertaking shift work.
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Besides the effect on blood pressure, the team found those who took the medication at bedtime also showed better kidney function and cholesterol measures, both of which are important factors when it comes to cardiovascular disease.