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7676360 
Journal Article 
Determination of efavirenz, a selective non-nucleoside reverse transcriptase inhibitor, in human plasma using HPLC with post-column photochemical derivatization and fluorescence detection 
Matthews, CZ; Woolf, EJ; Mazenko, RS; Haddix-Wiener, H; Chavez-Eng, CM; Constanzer, ML; Doss, GA; Matuszewski, BK 
2002 
Yes 
Journal of Pharmaceutical and Biomedical Analysis
ISSN: 0731-7085
EISSN: 1873-264X 
PERGAMON-ELSEVIER SCIENCE LTD 
OXFORD 
28 
5 
925-934 
English 
12039635 
WOS:000176207800015 
Methods for the quantitative determination of efavirenz in human plasma and the qualitative assessment of the stereochemical integrity of efavirenz in post-dose human plasma samples are described. After the addition of an internal standard, plasma samples were extracted with hexane-methylene chloride (65/35, v/v%). The extracts were evaporated to dryness and reconstituted in mobile phase. Upon exposure to UV light, the analyte was found to form fluorescent products; the major fluorescent product was isolated and identified as a substituted quinoline. Thus, the plasma extracts were analyzed via HPLC with post-column photochemical derivatization and fluorescence detection. Reverse phase chromatography was used for the quantitative assay, whereas chromatography with a column containing a chiral stationary phase (dinitrobenzoyl leucine) was used for the stereochemical assessment. The quantitative assay has been validated in the concentration range of 50-1000 ng/ml using 0.5 ml samples. Analyte recovery was better than 89% at all points on the standard curve. Intra-day precision was better than 5% C.V., while accuracy was between 95 and 104% of nominal over the range of the assay. The selective detection method reduces the likelihood of interference by co-administered medications or endogenous species. The stereochemical configuration of efavirenz was confirmed to remain intact in post-dose human plasma samples. The quantitative method has been successfully utilized to support a study in which a possible drug interaction between co-administered HIV protease inhibitors and efavirenz was evaluated. 
efavirenz; analysis; plasma; fluorescence; photochemistry; stereochemistry; HPLC