title: Development of an assay for the simultaneous determination of sildenafil (Viagra) and its metabolite (UK-103,320) using automated sequential trace enrichment of dialysates and high-performance liquid chromatography.
abstract: The development of the ASTED (automated sequential trace enrichment of dialysates) system to prepare plasma samples prior to high-performance liquid chromatography (HPLC) of sildenafil and its demethylated metabolite (UK-103,320) is described. Investigations to elucidate potential pitfalls of the ASTED on-line sample preparation system prior to separation of the analytes by HPLC are presented. The procedure is shown to be selective for sildenafil and UK-103,320, and linear over the range 1.00-250 ng/ml. The intra-batch imprecision (C.V.) of the method at plasma analyte concentrations of 1.00, 5.00, 50.0 and 200 ng/ml was 11.2, 3.10, 1.50, and 1.30%, respectively, and the corresponding inter-batch imprecision was estimated to be 13.5, 7.09, 3.69, and 5.43%. At these plasma analyte concentrations the overall inaccuracy (% bias) of the procedure ranged from 3.6 to 8.4%. The method showed similar assay performance for the estimation of the metabolite, UK-103,320. The application of the assay to a pharmacokinetic investigation during a clinical study is presented.
authors.affiliation: Clinical Innovations Ltd., Stareton, Kenilworth, Warwickshire, UK.
authors.forename: J D
authors.initials: JD
authors.lastname: Cooper
authors.forename: D C
authors.initials: DC
authors.lastname: Muirhead
authors.forename: J E
authors.initials: JE
authors.lastname: Taylor
authors.forename: P R
authors.initials: PR
authors.lastname: Baker
mesh_terms: D002851:Chromatography, High Pressure Liquid; D018592:Cross-Over Studies; D003956:Dialysis; D004355:Drug Stability; D006801:Humans; D010726:Phosphodiesterase Inhibitors / Q000097:blood* / Q000493:pharmacokinetics; D010879:Piperazines / Q000097:blood* / Q000493:pharmacokinetics; D011687:Purines; D011744:Pyrimidinones / Q000097:blood*; D051437:Renal Insufficiency / Q000378:metabolism; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D000068677:Sildenafil Citrate; D013450:Sulfones
chemical_list: D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D011744:Pyrimidinones; D013450:Sulfones; C109995:UK 103320; D000068677:Sildenafil Citrate