Study objective: To determine if one commercial extended-release formulation of nifedipine (Adalat CC) is as effective as another (procardia XL) in controlling blood pressure over 24 hours.
Design: Open-label, randomized, crossover study.
Setting: University-affiliated family medicine clinic.
Patients: Fifteen patients with stage 1-4 primary hypertension.
Interventions: Procardia XL or Adalat CC once/day was titrated to achieve blood pressure control. The effective dose was continued for 4 weeks, washed out for 1 week, and reinstituted with other study drug.
Measurements and main results: Twenty-four-hour ambulatory blood pressure was recorded the conclusion of each treatment phase. Treatment phases were compared for mean 24-hour blood pressure, mean daytime (6:00 A.M.-10:00 P.M.) and mean nighttime blood pressure, and mean blood pressure load (percentage of blood pressure measurements > 140/90 mm Hg daytime and > 120/80 mm Hg nighttime). Thirteen patients completed the study. No statistically significant difference was seen in mean 24-hour blood pressure (138/86 mm Hg for Procardia XL vs 137/85 mm Hg for Adalat CC), daytime or nighttime blood pressure, or blood pressure load. Two patients experienced clinically significant adverse effects while taking Adalat CC.
Conclusions: In these patients with primary hypertension, Adalat CC was as effective as Procardia XL at controlling blood pressure for 24 hours. Blood pressure, heart rate, and adverse effects should be monitored 2-4 weeks after any exchange of Adalat CC for Procardia XL.