[Evaluation of the antihypertensive effect of capsule and tablet forms of nifedipine in moderate hypertension]

Abstract

The antihypertensive effect of nifedipine which has a preferential antagonistic action in the calcium channels of vascular smooth muscle was studied in several series of patients. A preliminary double-blind placebo study in 7 moderate hypertensive patients showed that a 10 mg capsule of nifedipine induced a significant fall in systolic and diastolic pressures (max. - 14%) which persisted for 3 hours in ambulatory patients. A crossover trial against captopril (1 mg/kg) in 12 moderately hypertensive patients illustrated the antihypertensive effects of 2 capsules (20 mg) of nifedipine. The onset of action was faster and the effects, which were more intense than those of captopril, lasted several hours. A double-blind crossover trial against placebo was performed with 3 doses (20, 40, 60 mg) of a tablet form of nifedipine in 8 hypertensive patients. The degree and duration of the fall in blood pressure depended on the dosage: - 11% and 7 hours with 20 mg; - 14% and 10 hours with 40 mg and - 18% and 12 hours with 60 mg. This study demonstrated a direct relationship between the plasma concentration of nifedipine and the associated fall in mean blood pressure. Finally, in a chronic study of 20 hypertensive patients receiving 2 X 20 mg daily of the tablet form of nifedipine alone for 3 weeks, an 8% fall in blood pressure was observed, normalising the values in 50% of cases. Patients who remained hypertensive were given 2 X 40 mg of the nifedipine tablets for another 3 weeks and an additional 7% fall in blood pressure was observed.(ABSTRACT TRUNCATED AT 250 WORDS)