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Biomedical subjects

P E Stanley

Publications and source records attributed to P E Stanley.

7 recordsLinked to original sources
PubMed1978

Interference in assays for hydralazine in humans by a major plasma metabolite, hydralazine pyruvic acid hydrazone.

The present study showed that published spectrophotometric and GLC methods for hydralazine in plasma do not distinguish between the drug and a major plasma metabolite, hydralazine pyruvic acid hydrazone. These methods involve the acid treatment of the sample, which hydrolyzes that hydrazone back to hydralazine. A specific GLC assay for the hydrazone was developed and involves its selective extraction from plasma and transformation to 3-trifluoromethyl-s-triazolo[3,4-a]phthalazine. This derivative could be sensitively measured by GLC using an electron-capture detector. With this procedure, it was shown that most "apparent hydralazine" in plasma is the hydrazone, which forms rapidly from hydralazine and endogenous pyruvic acid. Previous work indicated that the hydrazone was inactive when administered intravenously to rabbits.

Chromatography, Gas↗
PubMed1978

Determination of phenytoin in plasma: a comparison of procedures using a new radioimmunoassay, gas chromatography, and enzyme immunoassay.

A new commercially available radioimmunoassay (RIA) procedure for the anticonvulsant drug phenytoin has been assessed and compared with a gas-liquid chromatographic (GLC) and an enzyme immunoassay (EMIT) procedure. One hundred and thirty-four plasma samples containing phenytoin were analyzed by the three methods and the results were found to be essentially independent of the procedure used and so would indicate similar clinical interpretation. The correlation coefficients were: RIA/GLC = 0.988; EMIT/RIA = 0.978; EMIT/GLC = 0.981. The cross reactivity of 33 drugs and related compounds was tested in the RIA and EMIT procedures and only a few very closely related substances showed significant cross reactivity. In addition, the three methods were compared with respect to the technical difficulties involved as well as time and cost for the assay of single and multiple samples.

Chromatography, Gas↗