Assessment of blood pressure control during once-a-day administration of antihypertensive drugs

The quality of blood pressure (BP) control during twice and once-a-day administration of antihypertensive drugs was evaluated in twenty-four patients with essential hypertension. They were treated over periods of several weeks with chlorthalidone and clonidine given twice a day and then received the total daily dose at once, at bedtime. BP was monitored over a 24-hour period with a semiautomatic device during both the twice- and one-daily dose, readings being taken at 7 a.m., 11 a.m., 1 p.m., 4 p.m., 7 p.m. and 10 p.m., and then compared. There was no statistically significant difference (p <0.25) in BP control between the b.i.d. and the q.d. schedule of antihypertensive therapy. It is concluded that smooth control of BP can be obtained in the treatment of mild or moderate, uncomplicated hypertension with a single daily dose of a combination of clonidine and chlorthalidone.