A randomized controlled trial on the blood pressure-lowering effect of amlodipine and nifedipine-GITS in sustained hypertension.

In a multicenter, randomized trial, we investigated whether the long half-time dihydropyridine calcium channel blocker amlodipine was more efficacious than the gastrointestinal therapeutic system (GITS) formulation of nifedipine in lowering ambulatory blood pressure (BP) in sustained hypertension (clinic systolic/diastolic BP 140-179/90-109 mm Hg and 24-hour systolic/diastolic BP ≥ 130/80 mm Hg). Eligible patients were randomly assigned to amlodipine 5-10 mg/day or nifedipine-GITS 30-60 mg/day. Ambulatory BP monitoring was performed for 24 hours at baseline and 4-week treatment and for 48 hours at 8-week treatment with a dose of medication missed on the second day. After 8-week treatment, BP was similarly reduced in the amlodipine (n = 257) and nifedipine-GITS groups (n = 248) for both clinic and ambulatory (24-hour systolic/diastolic BP 10.3/6.5 vs 10.9/6.3 mm Hg, P ≥ 0.24) measurements. However, after missing a dose of medication, ambulatory BP reductions were greater in the amlodipine than nifedipine-GITS group, with a significant (P ≤ 0.04) between-group difference in 24-hour (-1.2 mm Hg) and daytime diastolic BP (-1.5 mm Hg). In conclusion, amlodipine and nifedipine-GITS were efficacious in reducing 24-hour BP. When a dose of medication was missed, amlodipine became more efficacious than nifedipine-GITS.