The bioavailability of oral nifedipine formulations: a statistical and simulation approach.

The bioequivalence of three oral forms of nifedipine was assessed in a triple crossover study on 12 healthy volunteers. Single 10 mg dose was given and ten blood samples were drawn during the first 8 h after administration. Highly sensitive gas chromatographic method was used for the nifedipine assay.

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.

Gas and liquid chromatographic analyses of nimodipine calcium antagonist in blood plasma and cerebrospinal fluid.

Gas (GC) and liquid chromatographic (LC) assay procedures were developed for analysis of nimodipine (1,4-dihydropyridine calcium antagonist, BAY e 9736) in blood plasma at low nanogram concentration levels. To avoid decomposition during gas chromatography, nimodipine was oxidized to nimodipine pyridine (P) analogue before it was chromatographed on the OV-17 column and quantitated using an electron-capture detector. In contrast, the LC procedure involved chromatographic separation and quantitation of the underivatized nimodipine and of the endogenous P analogue using a 3-micron Spherisorb ODS column and UV detection.

Bioequivalence and metabolism of nitrendipine administered orally to healthy volunteers.

Relative bioavailability of 5-, 10-, and 20-mg nitrendipine tablets was determined in a four-way crossover bioequivalence study involving 22 normal male volunteers. Liquid suspension of nitrendipine was used as a reference. Plasma and urine samples collected during each study period were assayed by high performance liquid chromatographic and capillary gas chromatographic (GC) procedures for nitrendipine and the nitrendipine pyridine metabolite.

Pharmacokinetics and metabolism of nifedipine.

Nifedipine is almost completely absorbed from the gastrointestinal tract as shown by plasma levels after sublingual, oral, and rectal administration. Because of presystemic metabolism, the bioavailability is about 56% to 77%. After oral administration of 10 mg, the mean plasma concentration of nifedipine reaches maximum values of 160 +/- 49 micrograms/liter after 30 to 60 minutes.