Lofexidine in the treatment of hypertension: a twice-daily versus one-daily dose comparison with 24-hour blood pressure monitoring.

Lofexidine, an antihypertensive imidazoline derivative, was given to ten hypertensives on both a twice-daily and once-daily regimen, using routine blood pressure measurements and 24-hour Remler recording. Plasma renin activity and catecholamines were measured. After a dose titration with twice-daily doses, the total twice-daily dose was given once daily for two weeks and the drug abruptly withdrawn. Mean placebo blood pressure was 136/104 mm Hg supine. After twice-daily therapy, this fell to 118/86 mm Hg, and upon conversion to once-daily therapy, it rose to 126/89 mm Hg. With the Remler recorder, mean 24-hour blood pressure was 125/89 during the twice-daily therapy, 133/94 mm Hg during once-daily therapy, and 142/99 mm Hg on the day after acute withdrawal; i.e., evaluation in all three treatment periods showed a lack of sustained control with both a wide range and high frequency of blood pressure variation. Plasma renin activity and plasma epinephrine and norepinephrine did not change significantly during the study.