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

J Chromatogr B Biomed Sci Appl. 1997 Nov 7;701(1):87-95. doi: 10.1016/s0378-4347(97)00339-3.


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.

Publication types

  • Clinical Trial
  • Clinical Trial, Phase I
  • Clinical Trial, Phase II
  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Chromatography, High Pressure Liquid
  • Cross-Over Studies
  • Dialysis
  • Drug Stability
  • Humans
  • Phosphodiesterase Inhibitors / blood*
  • Phosphodiesterase Inhibitors / pharmacokinetics
  • Piperazines / blood*
  • Piperazines / pharmacokinetics
  • Purines
  • Pyrimidinones / blood*
  • Renal Insufficiency / metabolism
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Sildenafil Citrate
  • Sulfones


  • Phosphodiesterase Inhibitors
  • Piperazines
  • Purines
  • Pyrimidinones
  • Sulfones
  • UK 103320
  • Sildenafil Citrate