title: Differential assay of zidovudine and its glucuronide metabolite in serum and urine with a radioimmunoassay kit.
abstract: We developed an ancillary procedure for the ZDV-Trac RIA (Incstar) to allow simultaneous determination of both zidovudine (3'-azido-3'-deoxythymidine, ZDV, AZT, Retrovir) and its metabolite, the glucuronide of ZDV (3'-azido-3'-deoxy-5'-O-beta-D-glucopyranuronosylthymidine, ZDVG, GAZT), in human serum and urine. Using the ZDV-Trac RIA, we measured ZDV concentrations before and after ZDVG in samples was hydrolyzed to ZDV by beta-glucuronidase (EC 3.2.1.31); ZDVG concentration was calculated as the difference between the two results. This method enables rapid evaluation of a large number of samples with a total turn-around time of 6 h. The lower detection limit of the RIA was 0.27 micrograms/L; the measurements varied linearly with ZDV concentrations from 0.27 to 217 micrograms/L, with the 50% inhibitory concentration being approximately 10 micrograms/L. Analytical recoveries of inhouse serum and urine controls for both ZDV and ZDVG exceeded 90%. Coefficients of variation (CVs) of serum controls were less than 6% for ZDV and less than 11% for ZDVG; for urine controls, CVs for both ZDV and ZDVG were less than 6%. Results for ZDVG concentrations obtained by HPLC and by the ZDV-Trac RIA system compared well: r = 0.978, slope 1.0, for serum samples, and r = 0.993, slope 1.09, for urine samples.
authors.affiliation: Experimental Therapy Division, Burroughs Wellcome Co., Research Triangle Park, NC 27709.
authors.forename: S M
authors.initials: SM
authors.lastname: Tadepalli
authors.forename: L
authors.initials: L
authors.lastname: Puckett
authors.forename: S
authors.initials: S
authors.lastname: Jeal
authors.forename: L
authors.initials: L
authors.lastname: Kanics
authors.forename: R P
authors.initials: RP
authors.lastname: Quinn
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000188:drug therapy / Q000378:metabolism*; D005965:Glucuronates / Q000032:analysis*; D006801:Humans; D008991:Monitoring, Physiologic; D011863:Radioimmunoassay; D011933:Reagent Kits, Diagnostic; D015215:Zidovudine / Q000032:analysis* / Q000627:therapeutic use
chemical_list: D005965:Glucuronates; D011933:Reagent Kits, Diagnostic; D015215:Zidovudine