Efficacy of a low dose nifedipine GITS (20 mg) in patients with mild to moderate hypertension.

Nifedipine gastrointestinal therapeutic system (GITS) is a once-a-day formulation of nifedipine providing stable plasma concentrations over the entire 24 h dosing interval. The antihypertensive efficacy of a new 24 mg formulation was evaluated in 187 patients in 15 centres across the country. After a two-week placebo washout, mild to moderate hypertensive patients were randomized in a double-blind, parallel design to four weeks of placebo or nifedipine GITS 20 mg once daily treatment. Changes in office blood pressure (BP) were noted for each group. Ambulatory BP was also monitored at baseline and after four weeks of placebo/nifedipine therapy in a subgroup of 66 patients at five centres. After four weeks of treatment, office BP in the placebo group decreased by 5.0 +/- 11.9/5.4 +/- 7.9 mmHg compared with 9.3 +/- 11.2/8.6 +/- 7.4 mmHg in the nifedipine GITS group. Both systolic and diastolic BP were significantly decreased (P = 0.006 and P = 0.001 for systolic and diastolic, respectively) more with nifedipine GITS. Heart rate did not significantly differ between the groups at baseline nor after four weeks of treatment. The percentage of responders--defined as having a sitting diastolic BP less than 90 mmHg or a decrease from baseline of 10 mmHg--was 57% for nifedipine GITS versus 32% for placebo (P < 0.05). Daytime average diastolic blood pressure was 86.4 +/- 6.4 mmHg in the nifedipine GITS 20 mg group compared with 93.7 +/- 8.9 mmHg in the placebo group (P < 0.02). The maximum antihypertensive effect of nifedipine during ambulatory monitoring was similar to the reduction in BP observed in the office at the end of the dosing interval. The frequency of spontaneously reported adverse events was similar for nifedipine GITS (32.3%) and placebo (37.2%). These results indicate that 20 mg of nifedipine GITS is efficacious in decreasing BP, with good 24 h control and an incidence of adverse events similar to that of placebo-treated patients.