Pharmacokinetic evaluation of conventional and controlled-release product of naproxen. Quantitative determination of dextran-naproxen ester pro-drugs with varying molecular weights and degrees of substitution in biological media by means of high-performance size exclusion chromatography with fluorescence detection. Metabolic chiral inversion of anti-inflammatory 2-arylpropionates: lack of reaction in liver homogenates, and study of methine proton acidity. Rx drugs

Drugs online research references

Drugs Exp Clin Res. 1990;16(5):243-7.
Pharmacokinetic evaluation of conventional and controlled-release product of naproxen.

Palazzini E, Galli G, Babbini M.

Alfa Wassermann S.p.A., Bologna, Italy.

The bioavailability and pharmacokinetics of a new controlled-release tablet (CRT) of naproxen (750 mg tablet) have been determined, relative to an equivalent dose of conventional product (CT), by a cross-over study in twenty healthy volunteers. The two dosage forms were bioequivalent in terms of total AUC; however, the Cmax of the controlled-release product was lower, and the Tmax longer than that of the conventional product. The mean residence time and the absorption and elimination half-lives of the CRT were also substantially longer than those of the CT. The pharmacokinetic features offered by the novel formulation suggest that it may be suitable for once-daily dosing.

online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2078990&dopt=Abstract

J Pharm Biomed Anal. 1989;7(10):1173-81.
Quantitative determination of dextran-naproxen ester pro-drugs with varying molecular weights and degrees of substitution in biological media by means of high-performance size exclusion chromatography with fluorescence detection.

Larsen C.

Department of Pharmaceutics, Royal Danish School of Pharmacy, Copenhagen, Denmark.

A high-performance size exclusion chromatographic procedure using a Nucleosil Diol column and fluorescence detection has been developed for the determination of dextran-naproxen ester pro-drugs with varying molecular weights and degrees of substitution in aqueous buffer solutions and biological media in the presence of the parent drug. The effect of several variables on the chromatographic behaviour of the compounds is discussed. Linear standard calibration curves were constructed for all the dextran derivatives incubated in whole blood and urine (human and rabbit), rabbit liver homogenate and human synovial fluid. In whole blood, the detection limit (lambda ex = 330 nm, lambda em = 360 nm) for a dextran T-70 pro-drug with a degree of substitution (DS) of 10.6 was found to be 2 micrograms ml-1 after applying a 20-micrograms sample to the column. The assay has been used in stability studies and determination of plasma concentration-time profiles after intravenous administration to rabbits of dextran-naproxen ester pro-drugs.

online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2484990&dopt=Abstract

Xenobiotica. 1988 May;18(5):533-43.
Metabolic chiral inversion of anti-inflammatory 2-arylpropionates: lack of reaction in liver homogenates, and study of methine proton acidity.

Mayer JM, Bartolucci C, Maitre JM, Testa B.

School of Pharmacy, University of Lausanne, Switzerland.

1. Enrichment in the (S)-enantiomers for (R)-flurbiprofen, (R)-naproxen, (R)-suprofen and (R;S)-ibuprofen was investigated in various subcellular hepatic preparations containing coenzyme A. While such preparations were able to form hippuric acid from benzoic acid, the chiral inversion was never seen. 2. Using 2-dimethylaminoethanethiol 2-phenylpropionate (DEPP) as a model acyl thioester, the acidity of the methine proton was investigated by monitoring the proton/deuterium exchange occurring in deuterated solvents using high-resolution n.m.r. The compound was inert up to 22 h in D2O at 37 degrees C and pD 7.4. In pure methanol or a methanol-water mixture, only solvolysis was seen. In contrast, competitive hydrolysis (k = 0.005 h-1) and proton/deuterium exchange (k = 0.09 h-1) were seen in a CD3CN/D2O (50:50) mixture at 37 degrees C. 3. It is speculated that the failure to characterize chiral inversion of 2-arylpropionates in subcellular preparations may be due to the absence of a microenvironment of adequately moderate polarity.

online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2840782&dopt=Abstract

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