Morning versus evening administration of nifedipine gastrointestinal therapeutic system in the management of essential hypertension.

The nifedipine gastrointestinal therapeutic system (GITS) is a recently developed controlled-release formulation for once-a-day dosing. We evaluated the influence of morning versus evening administration of the drug in a randomized double-blind cross-over study including 15 essential hypertensives. Five patients had to be excluded from blood pressure analysis because of noncompliance (three cases) or intolerable side effects (two cases). To assess the exact duration of the antihypertensive efficacy noninvasive automatic ambulatory blood pressure monitoring was performed. After a placebo period patients were given 30 mg nifedipine GITS either at 1000 or 2200 hours. Twenty-four-hours systolic and diastolic blood pressure profiles documented a sustained antihypertensive effect of both nifedipine regimens throughout the whole period without affecting the circadian rhythm. Statistical analysis revealed no significant difference between morning and evening administration. Two patients stopped their medication because of intolerable side effects (fatigue and muscle cramps, respectively). Two more cases suffered from mild reversible headache which provoked no discontinuation of the drug. In conclusion our results document a sustained antihypertensive efficacy of 30 mg nifedipine GITS in patients with moderate essential hypertension. Time of administration has no impact on day- and nighttime blood pressure control.