eMedicineLive

Almost 20% of the people around the world are affected by hypertension. It is one of the main reasons behind the incidence of cardiovascular disease.  Physicians generally employ antihypertensive medicines from the following six groups for better control of blood pressure: diuretics, calcium channel blockers, angiotensin converting enzyme inhibitors (ACE inhibitors), beta adrenergic receptor blockers, alpha adrenergic receptor blockers and angiotensin II receptor blockers. According to WHO recommendations, once daily long acting antihypertensive medicines help in achieving a better control of the blood pressure. However, the correct time of administration of antihypertensive medicines, whether morning or evening, has always been a point of debate among the physicians. A new Cochrane study has found that evening administration of medicines helps in a better control of the 24 hour blood pressure.

A meta- analysis of 21 randomized controlled trials involving 1,993 patients of primary hypertension was done under the leadership of Peng Zhao from the Sichuan University, Chengdu, China. Although the researchers did not find any significant difference in the morning systolic blood pressure and the morning diastolic blood pressure depending upon the time of administration of antihypertensive medicines, there was a significant statistical difference in the 24 hour blood pressure. The timing of medicines did not seem to affect the overall mortality rate, or the incidence of cardiovascular diseases.

In humans, the blood pressure is variable throughout the day and exhibits a circadian rhythm. It is usually lower at the end of the day and rises abruptly in the morning. However, this cycle is reversed in people who work night shifts. Earlier studies have indicated that this morning surge in the blood pressure is associated with increased incidence of myocardial infarctions and other conditions of the heart. Therefore doctors aim to administer antihypertensive medicines in a manner which can prevent this morning surge apart from controlling blood pressure throughout the day.

References:

http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD004184.pub2/full