Antihypertensive effect of diltiazem administered once and twice daily.

This study was undertaken to compare the antihypertensive effect of diltiazem administered once or twice daily. After a two week wash-out period, eight hypertensive patients were treated for two consecutive four week phases with 180 mg once daily or 90 mg twice daily of a sustained-release formulation of diltiazem. The sequence of the treatments was randomised and the trial carried out in a double-blind fashion. Ambulatory daytime BP profiles were obtained using a portable BP recorder (Remler M2000). The average of all BP readings taken during the monitoring period was 159/104 +/- 21/10 mgHg (mean +/- SD) at the end of the wash-out period and 145/90 +/- 20/12 and 148/95 +/- 21/11 mmHg under treatment with diltiazem 180 mg once daily and 90 mg twice daily, respectively. These data indicate that 180 mg of a slow-release formulation of diltiazem are as effective in lowering the BP of hypertensive patients when administered daily in a single dose as when divided into two doses.