Issue 105 Item 1 Aspirin at Bedtime is More Effective

It has been shown that taking aspirin at bedtime as other benefits for those with hypertension. Taking aspirin before bedtime–but not at other times of the day–may lower blood pressure in patients with mild hypertension as well as in pregnant women at risk for a dangerous blood pressure-related complication, researchers reported here on Wednesday.

It seems that people who take aspirin first thing in the morning get virtually no blood pressure benefit from the drug. As such, patients who consult with their doctor and decide to take aspirin for such conditions should only do so at night, according to Dr. Ramon D. Hermida of the University of Vigo, Spain. Most pregnant women are told to avoid taking aspirin because it can increase the risk of bleeding.

"Basically, there is no effect when aspirin is taken when waking up, and there is a significant effect when aspirin is taken at bedtime," Hermida said here at the Annual Scientific Meeting of the American Society of Hypertension.

Aspirin is already taken in low doses by many heart disease patients to prevent clotting.

In one study, Hermida and his team measured the effect of 100 milligrams of aspirin taken at different times each day starting in the first 12 to 16 weeks of pregnancy by 341 women at high risk of preeclampsia, a complication marked by high blood pressure. If left untreated, preeclampsia can develop into eclampsia, a life-threatening condition in which a woman has convulsive seizures in late pregnancy or during the first week after delivery. Preeclampsia is relatively common, affecting as many as 1 in 10 pregnancies.

Women at high risk of preeclampsia included those with a family history of the condition, and those who had developed preeclampsia during an earlier pregnancy.

The investigators found that women who took aspirin upon awakening had a 16% chance of developing preeclampsia–similar to that seen in women who took an inactive placebo pill. However, Hermida and his colleagues found that only 2% of women who took aspirin at bedtime developed preeclampsia during their pregnancies.

In a similar study of 78 patients with mild hypertension, Hermida and his team measured blood pressure for 48 consecutive hours before and after the patients had spent 3 months following a blood pressure-lowering diet alone, the diet and taking 100 milligrams of aspirin upon waking, or the diet and taking the aspirin before bedtime.

After 3 months, patients who took aspirin upon waking had no change in blood pressure, and those who simply followed dietary recommendations experienced a small improvement in their hypertension. In contrast, patients who took aspirin before bedtime in addition to the diet experienced a decrease in systolic blood pressure–the upper number in a blood-pressure reading–by an average of 7.6 millimeters of mercury (mm Hg) and a decrease in diastolic blood pressure, the bottom number, by an average of 6.1 mm Hg.

Dr. Hermida, explained that "such a simple thing" as changing when you take aspirin produces such a positive effect on blood pressure because it times the drug’s peak effects to when it is most needed.

Aspirin has its peak effects 4 to 6 hours after it is taken, Hermida explained, and the activity of potential clot-forming platelets is highest a few hours before waking from a night’s sleep. Furthermore, levels of the protein angiotensin, which constricts blood vessels and increases blood pressure, tend to be higher in the early morning hours, as well.

"So basically, you are targeting the time of the day when all these factors that increase your risk are high," Hermida said.

Previous studies have investigated whether aspirin might help prevent preeclampsia, but had found varied results. Hermida said that past investigations did not control for the time aspirin was taken during the sleep cycle, which may explain the seemingly conflicting findings. This research was partially funded by Bayer, the company that makes aspirin.