Comparative pharmacokinetics and antihypertensive effects of the nifedipine tablet and capsule

The pharmacokinetics and antihypertensive effects of the nifedipine tablet and capsule have been examined in six male patients with diastolic pressure greater than 95 mm Hg despite metoprolol therapy. On two separate mornings, a 20 mg nifedipine tablet or 2 X 10 mg nifedipine capsules were administered with metoprolol 100 mg following a 12-h fast. Both capsule and tablet significantly reduced blood pressure (BP), with the maximum fall occurring at 45 min for the capsule and 4 h for the tablet. Two patients developed postural hypotension after the capsule and a third experienced flushing and palpitations. The maximum nifedipine plasma concentration after the capsule was 257 ng/ml compared with 50 ng/ml for the tablet, and the time of maximum concentration was significantly earlier for the capsule. Although the nifedipine capsule results in a fivefold higher maximum plasma concentration and is associated with a more rapid reduction in blood pressure than the tablet, its use may be limited by postural hypotension and other untoward symptoms.