Stereoselective inversion of (R)-fenoprofen to (S)-fenoprofen in humans.

The concentrations of the (R)- and (S)-enantiomers of fenoprofen (alpha-methyl-3-phenoxy-benzeneacetic acid) were measured in plasma and urine of volunteers after oral administration of the (R,S)-racemate. In addition, urinary concentrations of the (R)- and (S)-4'-hydroxy metabolite of fenoprofen, the major metabolite, were measured. The (R)-enantiomer of fenoprofen was stereoselectively inverted to (S)-fenoprofen, which was the major isomeric form found in plasma and urine.

Liquid-chromatographic determination of penbutolol and its principal metabolites in plasma and urine.

We describe a sensitive, specific liquid-chromatographic determination of penbutolol and its 4-hydroxy metabolite in plasma and urine. The method involves a simple organic extraction, evaporation of the solvent, reconstitution in methanol/water, and injection into the chromatograph. Penbutolol, its metabolites, and the internal standard, propranolol, are resolved on a CN reversed-phase column and detected fluorometrically.

Linear pharmacokinetics of orally administered fenoprofen calcium.

The bioavailability of fenoprofen from three different fenoprofen calcium capsule formulations containing the equivalent of 60, 165, and 300 mg of fenoprofen was determined in two studies. In the first study, 12 subjects received one capsule of each formulation according to a three-period crossover design. The second study required each of 13 subjects to receive 300 mg of fenoprofen equivalent of the 60- and 300-mg capsules and 330 mg of the 165-mg capsule.

Benoxaprofen, a new anti-inflammatory agent: particle-size effect on dissolution rate and oral absorption in humans.

The particle-size effect of benoxaprofen, a new nonsteroidal anti-inflammatory agent, on the in vitro dissolution rate and oral absorption in humans was evaluated. Ten normal subjects participated in a randomized crossover-designed absorption study with two sieved particle-size formulations: one with crystals larger than 60 mesh (mean equivalent spherical diameter = 640 micron) and the other with crystals smaller than 100 mesh (mean equivalent spherical diameter = 67 micron). Plasma drug concentrations and urinary drug excretion were used to determine the relative absorption of the two formulations.

GLC determination of ethinamate and its hydroxy derivative in biological fluids.

A sensitive, specific GLC assay was developed for the determination of ethinamate in plasma and its major metabolite, trans-4-hydroxyethinamate, in urine. The assay uses a mass internal standard of dimethylethinamate. Ethinamate is extracted from alkalinized plasma with dichloromethane.