Once versus twice daily antihypertensive medications for the control of nocturnal blood pressure: a comparative study

Background Blood pressure (BP) shows short-term variability within the 24 h, which can only be assessed with 24-h ambulatory blood pressure monitoring (ABPM). It is of utmost importance to control BP throughout the night to reduce incidence of hypertension complications. The purpose of this study is to evaluate the effect of timing and frequency of antihypertensive medications on the average nighttime and 24-h blood pressure control. Results The study enrolled 199 hypertensive patients with controlled office blood pressure; 135 (67.8%) patients were on once daily antihypertensive medication (group 1) while 64 (32.2%) patients were on twice daily doses (group 2). The mean office SBP was 128.7 +/- 7.8 mmHg in group 1 vs 129.6 +/- 6.6 mmHg in group 2, (p = 0.421). ABPM readings for both groups were as follows: mean daytime SBP was 125.4 +/- 11.6 mmHg vs 130.1 +/- 12.9, p = 0.011; mean nighttime SBP was 117.0 +/- 12.4 mmHg vs 123.1 +/- 13.9 mmHg, p = 0.002, and mean 24-h SBP was 122.7 +/- 10.6 mmHg vs 127.5 +/- 12.0, p = 0.005. The prevalence of non-dipping was 68.9% in group 1 vs 70.3% in group 2 patients, p = 0.8 (the mean dipping ratio was 0.93 +/- 0.08 in group 1 vs 0.95 +/- 0.07 in group 2, p = 0.198). The prevalence of masked hypertension was higher in group 2 (28.1% vs 43.8%, p = 0.029). Conclusion Taking an extra antihypertensive pill at night did not show a decrease in the nighttime or the average 24H blood pressure in hypertensive patients with controlled office BP. On the contrary, patients who used twice daily antihypertensive medications seem to have higher nighttime and 24-h SBP, although the dipping ratio was comparable in both groups.