Is It Better to Take Antihypertensive Meds in the Evening?

Circadian rhythms are physical, mental and behavioral changes that follow, roughly, a 24-hour cycle.  The blood pressure has a distinct 24-hour rhythm, typically showing a morning surge on getting out of bed; some studies have suggested that this surge is linked to the occurrence of heart attacks, which are generally more frequent in the early hours following awakening. So the question arises, would the administration of antihypertensive medications in the evening be more effective in suppressing this morning surge, and thus more likely to reduce the risk of cardiovascular events. Researchers have now published a meta-analysis of clinical information on this topic in the Cochrane Reviews. 

To be included in the meta-analysis, studies had to be randomized, controlled trials comparing the effects of evening vs. morning once-a-day dosing regimens in patients with high blood pressure. Patients with known secondary hypertension (i.e. secondary to another health condition), shift workers or ‘white-coat hypertension’ were excluded.

Using these criteria, 21 studies covering 1,993 patients were analyzed.  The antihypertensives included were ACE-inhibitors, ARBs, calcium-channel blockers, diuretics, alpha-blockers, and beta-blockers.

It was found that taking antihypertensives in the evening was associated with a significant reduction in the average 24-hour blood pressures, compared with morning administration.  The average reductions were 1.71 mm Hg (systolic) and 1.38 mm HG (diastolic).  No significant differences were reported for morning systolic and diastolic pressures with different times of medication. And there was no significant difference in overall adverse events or withdrawals due to adverse events.

What was depressing about the studies was that none of them reported all-cause mortality, cardiovascular mortality, cardiovascular events or other serious adverse events.  The meta-analysis clearly suggested that better blood pressure control was achieved with evening dosing, but the clinical significance of this wasn’t examined. As we so often hear, more research is needed.