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Biomedical subjects

D G Kaiser

Publications and source records attributed to D G Kaiser.

At least 37 records · Page 2Linked to original sources
PubMed1976

Isomeric inversion of ibuprofen (R)-enantiomer in humans.

Enantiomeric compositions of the major urinary metabolites of ibuprofen [(RS)-2-(4-isobutylphenyl)propionic acid]were characterized after oral administration of the racemic mixture and oral administration of the individual enantiomers to normal human volunteers. Resolution of the diastereomeric amides, formed by reaction of the urinary metabolites with (S)-(-)-alpha-methylbenzylamine, was achieved by GLC. Only the (R)-(-)-enantiomer of the intact drug was inverted to its optical antipode, (S)-(+), in humans. However, both (S)-(+)- and (R)-(-)-enantiomers of the intact drug were transformed independently in vivo to the major metabolites, i.e., 2,4'-(2-hydroxy-2-methylpropyl)phenylpropionic acid and 2,4'-(2-carboxypropyl)phenylpropionic acid. In vivo metabolism of ibuprofen to its carboxy metabolite was not stereoselective.

Adult↗
PubMed1976

Fluorometric determination of trifluoromethyl-substituted 2,3-bis(4-methoxyphenyl)indoles in biological materials.

Interest in the 5-, 6-, and 7-trifluoromethyl-substituted 2,3-bis(4-methoxyphenyl)indoles as potent, orally active anti-inflammatory agents required a method for their determination in serum, urine, and feces to permit studies of their absorption, metabolism, and excretion. A simple, rapid, sensitive, and specific procedure was developed based on an ethyl acetate extraction of alkaline specimens and subsequent fluorometric analysis of ethanolic solutions of the extract residues. The method is sensitive to 0.1 microgram/ml, 0.5 microgram/ml, and 0.7 microgram/100 mg of these compounds in serum, urine, and feces, respectively. Overall mean recoveries and standard deviations of the 5-, 6-, and 7-trifluoromethyl-substituted compounds from biological samples were 102.2 +/- 3.0, 102.2 +/- 5.4, and 100.5 +/- 5.7%, respectively. The procedure was applied successfully to absorption studies with 2,3-bis(4-methoxyphenyl)-7-(trifluoromethyl)indole in the dog.

Animals↗
PubMed1975

GLC determination of ibuprofen [dl-2-(p-isobutylphenyl) propionic acid] enantiomers in biological specimens.

To study the behavior of the d- and l-isomers of ibuprofen in humans, a method for the determination of the individual enantiomers in plasma and urine was required. A specific procedure was developed based on (a) benzene extraction of the acidified specimens, (b) TLC of the benzene extract residue, (c) formation of the l-alpha-methylbenzylamides of the materials eluted from the chromatograms, and (d) quantification of the resulting diastereoisomeric amides by GLC in conjunction with flame-ionization detection. When using a 1-ml aliquot of the specimen, the method is sensitive to 1 mug of each enantiomer/ml of plasma or urine. As compared to simple aqueous solutions, the average recoveries of the enantiomers from plasma and urine ranged from 94 to96%. Mass spectrometric analyses, in conjunction with GLC, confirmed the specificity of the method for the intact enantiomers. The procedure was applied successfully to drug absorption studies in humans. After oral administration of the racemic mixture, the predominant enantiomer in peripheral circulation and excreted in urine was of the d-configuration.

Adult↗
PubMed1975

Fluorometric determination of 2,3-bis(p-methoxphenyl)imidazo(1,2-a)pyrimidine in biological materials.

Interest in 2,3-bis(p-methoxyphenyl)imidazo[1,2-a]-pyrimidine as a potent, orally active, anti-inflammatory agent required a method for its determination in serum, urine, and feces to permit studies of its absorption, metabolism, and excretion. A simple, rapid, sensitive, and specific procedure was developed based on an ethyl acetate extraction of alkaline specimens and subsequent fluorometric analysis of ethanolic solutions of the extract residues. The method is sensitive to 0.2 mug/ml, 0.3 mug/ml, and 1.2 mug/100 mg of drug in serum, urine, and feces, respectively. The overall mean recovery and the standard deviation from biological samples are 99.8 +/- 5.1%. The procedure has been successfully applied to absorption studies in the dog.

Animals↗
PubMed1975

0-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride as a sensitive derivatizing agent for the electron capture gas liquid chromatographic analysis of keto steroids.

0-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride was used to prepare oximes of steroids with keto groups in selected positions; 3,17 and 20-monoketo; 3,17 and 3,20-diketo. Some of the 3-keto steroids had hindered 17-hydroxyl groups which were not readily amenable to esterification with perfluoroanhydrides, the most commonly used derivatizing agents for electron capture gas chromatographic analysis of hydroxy steroids. The oximes were readily prepared from 5 ng of each of the compounds tested, and with testosterone it was demonstrated that the derivative could be prepared from as little as 0.1 ng. The derivatives were stable to gas chromatography and extremely sensitive to electron capture detection. The sensitivity ranged from 1.5 X 10(4) coulombs per mole of progesterone. Because of the ease of preparation of the derivatives, their stability in common solvents and analytical manipulative techniques, the reagent would be suitable for the micro analysis of biologically significant keto steroids by electron capture gas chromatography.

Chromatography, Gas↗