Therapeutics on the clock: Circadian medicine in the treatment of chronic inflammatory diseases

The circadian clock is a collection of endogenous oscillators with a periodicity of ~ 24 h. Recently, our understanding of circadian rhythms and their regulation at genomic and physiologic scales has grown significantly. Knowledge of the circadian influence on biological processes has provided new possibilities for novel pharmacological strategies. Directly targeting the biological clock or its downstream targets, and/or using timing as a variable in drug therapy are now important pharmacological considerations. The circadian machinery mediates many aspects of the inflammatory response and, reciprocally, an inflammatory environment can disrupt circadian rhythms. Therefore, intense interest exists in leveraging circadian biology as a means to treat chronic inflammatory diseases such as sepsis, asthma, rheumatoid arthritis, osteoarthritis, and cardiovascular disease, which all display some type of circadian signature. The purpose of this review is to evaluate the crosstalk between circadian rhythms, inflammatory diseases, and their pharmacological treatment. Evidence suggests that carefully rationalized application of chronotherapy strategies - alone or in combination with small molecule modulators of circadian clock components - can improve efficacy and reduce toxicity, thus warranting further investigation and use.

Chronotherapy for Hypertension

PURPOSE OF REVIEW

Given the emerging knowledge that circadian rhythmicity exists in every cell and all organ systems, there is increasing interest in the possible benefits of chronotherapy for many diseases. There is a well-documented 24-h pattern of blood pressure with a morning surge that may contribute to the observed morning increase in adverse cardiovascular events. Historically, antihypertensive therapy involves morning doses, usually aimed at reducing daytime blood pressure surges, but an absence of nocturnal dipping blood pressure is also associated with increased cardiovascular risk.

RECENT FINDINGS

To more effectively reduce nocturnal blood pressure and still counteract the morning surge in blood pressure, a number of studies have examined moving one or more antihypertensives from morning to bedtime dosing. More recently, such studies of chronotherapy have studied comorbid populations including obstructive sleep apnea, chronic kidney disease, or diabetes. Here, we summarize major findings from recent research in this area (2013-2017). In general, nighttime administration of antihypertensives improved overall 24-h blood pressure profiles regardless of disease comorbidity. However, inconsistencies between studies suggest a need for more prospective randomized controlled trials with sufficient statistical power. In addition, experimental studies to ascertain mechanisms by which chronotherapy is beneficial could aid drug design and guidelines for timed administration.

Evaluation of the antihypertensive effect of nocturnal administration of acetylsalicylic acid: a cross-over randomized clinical trial

OBJECTIVE

Several studies have shown that evening intake of aspirin has antihypertensive effect in healthy adults, which has not been proven in patients with cardiovascular disease, who mostly take aspirin in the morning. We have evaluated the antihypertensive effect of bedtime administration of aspirin in patients with cardiovascular disease already treated for hypertension.

METHODS

This is a multicenter randomized triple-blind placebo-controlled crossover trial, with hypertensive patients treated with aspirin for secondary prevention. There was a baseline-randomized assignment to 2-month periods of bedtime aspirin (100 mg) first and morning-time aspirin later, or inversely, both periods separated by an open label 2-4 weeks period of morning-time aspirin. At the start and end of each treatment period, a 24-h ambulatory blood pressure monitoring was performed. The main outcome measure was mean 24-h blood pressure. The analyses were performed according to the intention-to-treat principle.

RESULTS

Overall, 225 patients were randomized. No significant differences were observed in ambulatory blood pressure by time of intake of usual low doses of aspirin. The mean SBP/DBP was 123.2/69.9 (95% CI 121.58-124.9/68.86-76.86) with bedtime administration and 122.4/68.8 (95% CI 120.76-124.01/67.85-69.83) with daytime administration (P = 0.3 and P = 0.23 for SBP and DBP, respectively).

CONCLUSION

Administering aspirin at bedtime rather than in the morning does not modify the 24-h ambulatory blood pressure in hypertensive patients in secondary cardiovascular prevention.The trial was registered with ClinicalTrials.gov (number NCT01741922).