Friday, July 01, 2011


It is traditionally belief that blood pressure medications should be taken in the morning, if it is once a day, and the daytime, if it is two or three times a day. Nowadays, the pharmaceutical companies are so good that almost all drugs are once a day, and also in combination, so that you do not have to carry two or three BP pills, just one, maybe two pills.
However, this does go against the body physiology as we know it currently. We know that there is a circadian BP pattern, that BP seems to spike as we awaken, in the early hours of the morning. We also know that many cardiovascular events, meaning heart attacks, and strokes, tend to occur, in the early hours of the morning. It seems that the Renin-Angiotensin-aldosterone system is stimulated at night ( I wonder why ), and so blocking the RAAS system at night makes sense.
In my reading, I picked up a study, done in Spain, that seem to suggest that there is much benefit in taking your blood pressure pills at night, before bedtime. The same group did two studies. The earlier study called MAPEC ( Ambulatory BP monitoring in prediction of cardiovascular events and effects of chronotherapy ). This study was publishes last year.
At the just concluded European Renal Association/European Dialysis and Transplant Association 2011 Congress, Dr Hermida RC presented a paper entitled "Influence of circadian time of blood pressure-lowering treatment on cardiovascular risk in resistant hypertension." They took out 776 patients with resistant hypertension, measure their ambulatory BP over 24 hours, gave half at least one BP medication at night and the other half their medications at the usual morning hour. After 8 years of followup, they found that those who take at least one BP medication at bedtime, had an event free survival of 81% compared to those who took their medications in the usual way ( 64% event free survival at 8 years ).
This will lend some proof to the original hypothesis that the active RAAS at night may be the cause of our problem, and so blocking the night surge, would make sense. I must say that I would like to see more work on this, as the data all seem to be coming out of the University of Vigo, Spain, by this group.
I do ask some of my patients to take their BP pills at night, but not routinely. In all hypertensives, I do routinely enquire about their sleep pattern as there are numerous study which showed that poor sleep, is correlated to poor BP control and also with more CV events.
So food for thought. Should we advocate taking BP pills at night, instead of the morning, and is there a downside. Looks like there may be an advantage.

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