Hypertension (HTN) and obstructive sleep apnea (OSA) are associated with increased risk for adverse cardiovascular events. Comorbid HTN with OSA is often resistant to pharmacologic treatment. Chronotherapy, the timing of treatment based on circadian rhythms, may prove to be a valuable, cost-effective tool for improving blood pressure (BP) control among those with OSA. This Systematic Review appraises the existing literature regarding morning (a.m.) vs. evening (p.m.) administration of antihypertensives among this population.
Ovid, PubMed, Embase, Scopus, and Cochrane were searched for studies examining nighttime administration or nighttime versus daytime administration of antihypertensive medications.
A variety of outcomes were examined. Of studies that examined average daytime and average nighttime BP, all except one found a significant decrease from baseline in both variables regardless of medication used or treatment time. Of four studies that examined BP dipping pattern, two found a significant increase in the percentage of participants with a normal dipping pattern, one reported a non-significant increase, and one reported no increase. One study and the case study report the effect on sleep BP surge secondary to hypoxemia and the natural early morning BP surge. The study found that the β-blocker carvedilol was more effective at lowering the hypoxia-induced sleep BP surge, while the calcium channel blocker nifedipine was more effective in lowering the natural morning BP surge. The case study found that the -blocker doxazosin was effective in lowering both measurements in one patient.
Findings suggest that nighttime versus daytime administration of antihypertensive drugs may have a greater impact on improving blood pressure metrics in adults with coexisting OSA and HTN. The current literature is insufficient to draw robust conclusions regarding the efficacy of chronotherapy in the targeted population. The success observed in some studies supports the examination of this intervention in future research.