7B.09: BLOOD PRESSURE LOWERING EFFICACY OF AMLODIPINE AND NIFEDIPINE-GITS IN AMBULATORY HYPERTENSION

Objective: 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 morning blood pressure in ambulatory hypertension. Design and method: The study was designed as a multicentre, randomized, parallel-group comparison trial in patients with stages 1 and 2 clinic (mean of 6 readings on 2 occasions off antihypertensive medication, systolic blood pressure 140–179 mm Hg and/or diastolic blood pressure 90–109 mm Hg) and ambulatory hypertension (24-hour mean blood pressure of at least 130 mm Hg systolic or 80 mm Hg diastolic). Eligible patients were randomly assigned to 8-week treatment with amlodipine 5 mg/day or with nifedipine GITS 30 mg/day, which could be up-titrated, respectively, to 10 mg/day or 60 mg/day at 4 weeks of follow-up. The primary efficacy variable was the change from baseline to the end of 8-week treatment in morning systolic blood pressure (4:00 to 8:00) of the first 24-hour ambulatory monitoring. Results: In the intention-to-treat analysis, blood pressure at 4 and 8 weeks of follow-up was similarly reduced in the amlodipine (n = 257) and nifedipine GITS (n = 248) groups for clinic measurement and 24-hour, daytime, night-time, and morning ambulatory measurements (P> = 0.07). However, amlodipine, compared with nifedipine GITS, was 2–3 mm Hg more efficacious in lowering ambulatory blood pressure within 4 hours of drug ingestion and after a dose of medication was missed (P< = 0.05). The results of the per-protocol analysis were confirmatory. Conclusions: Both amlodipine and nifedipine GITS are efficacious in reducing clinic and ambulatory blood pressure. However, when a dose of medication is delayed or missed, amlodipine, but not nifedipine GITS, remains efficacious in lowering blood pressure.