Bedtime Dosing Curbs Nondipper BP Patterns


SAN FRANCISCO — Patients on three or more medications for resistant hypertension were more likely to have blood pressure under control and less likely to have a nondipper blood pressure pattern at night if they took at least one of the drugs at bedtime, according to ambulatory blood pressure monitoring study involving 1,306 patients.

For 48 consecutive hours, a device automatically measured blood pressure and heart rate every 20 minutes from 7 a.m. to 11 p.m. and every 30 minutes during the night. Simultaneous wrist actigraphy was used to monitor physical activity every minute. A comparison of data from the two devices allowed investigators to determine blood pressure means during waking and sleep time according to each individual's rest-activity cycle.

Among 573 patients who took at least one of their antihypertensives at bedtime and the remainder in the morning, 32% had blood pressure under control, which was significantly better compared with 23% of the 733 patients who took no antihypertensive medications at bedtime and all of them on awakening, Dr. Ramon C. Hermida and his associates reported at the annual meeting of the American Society of Hypertension.

The bedtime-dose group also had significantly lower blood pressures at nighttime and morning, and lower ambulatory pulse pressure compared with the morning-only group. The bedtime group patients had a higher awake/asleep blood pressure ratio, and thus were significantly less likely to have a nighttime nondipper blood pressure pattern that has been associated with a higher risk of cardiovascular and cerebrovascular events. A nondipper blood pressure pattern is defined as less than a 10% decline in mean blood pressure during sleep compared with awake blood pressure.

In the bedtime group, 40% had a nondipper pattern, compared with 83% in the morning-only group, said Dr. Hermida of the University of Vigo, Spain.

In addition, the bedtime group had significantly lower mean levels of glucose, total cholesterol, LDL cholesterol, fibrinogen, and urinary albumin excretion.

In general, patients with resistant hypertension have a high prevalence of the nondipper blood pressure pattern. Conventional strategies for managing resistant hypertension focus on adding another drug or changing a drug to see if that improves the combination therapy.

Research findings suggest that up to 89% of patients who take antihypertensives ingest them all in the morning, including patients with resistant hypertension.

With better timing of medication administration, blood pressure control could be improved and the number of patients with the nondipper pattern reduced, Dr. Hermida proposed.

The investigators are studying whether this normalization of the blood pressure pattern might reduce cardiovascular risk beyond the benefits conferred by reducing mean blood pressure values.

In the current study, the cohort had a mean age of 61 years; 52% of the participants were male.

Mean morning blood pressures were 136/79 mm Hg in the bedtime group and 142/82 mm Hg in the morning group.

Mean glucose values were 116 mg/dL in the bedtime group and 121 mg/dL in the morning group. Mean values for total cholesterol and LDL cholesterol were 201 mg/dL and 129 mg/dL in the bedtime group, respectively, and 206 mg/dL and 134 mg/dL in the morning group, respectively.

Fibrinogen levels were 339 mg/dL in the bedtime group and 351 mg/dL in the morning group. In the bedtime group, the urinary albumin excretion rate was 29 mg/day, compared with 39 mg/day in the morning group.

There were no significant differences in heart rates between the groups.

An audience member pointed out that the researchers did not indicate which antihypertensives were being taken in the a.m. or the p.m., an observation that was relevant since not all medications are effective for a 24-hour period.

The investigators reported having no relevant conflicts of interest.

In the bedtime-dose group, 40% had a nondipper pattern, compared with 83% in the morning-only group.


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