Bioequivalence study of two tablet formulations of sildenafil

Arzneimittelforschung. 2008;58(3):122-5.


This study was conducted in order to assess the bioequivalence of two tablet formulations containing 100 mg sildenafil (1-[4-ethoxy-3-(6,7-dihydro-1-,ethyl-7-oxo-3-propyl-1H-pyrazolo[4,3-d]pyrimidin-5-yl)phenylsulphonyl] -4-methyl piperazine, CAS 139755-83-2). Twenty-eight healthy subjects were enrolled in a single-centre, randomised, single-dose, open-label, 2-way crossover study, with a minimum washout period of 7 days. Plasma samples were collected up to 18.0 h postdosing. Sildenafil levels were determined by reverse liquid chromatography coupled with tandem mass spectrometry detection (LC-MS/MS). Pharmacokinetic parameters used for bioequivalence assessment [area under the concentration-time curve from time zero to time of last non-zero concentration (AUC(last)) and maximum observed concentration (C(max)) were main evaluation criteria; however, the area under the concentration-time curve from time zero to infinity (AUC(inf)) was also analysed] were determined from the sildenafil concentration data using non-compartmental analysis. The 90% confidence intervals (obtained by analysis of variance, ANOVA) were 86.70-108.19 for C(max), 86.67-99.26 for AUC(last) and 87.19-99.82 for AUC(inf) within the predefined ranges. Bioequivalence between the two formulations was concluded both in terms of rate and extent of absorption.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adolescent
  • Adult
  • Area Under Curve
  • Chemistry, Pharmaceutical
  • Cross-Over Studies
  • Humans
  • Male
  • Piperazines / administration & dosage*
  • Piperazines / adverse effects
  • Piperazines / pharmacokinetics*
  • Purines / administration & dosage
  • Purines / adverse effects
  • Purines / pharmacokinetics
  • Sildenafil Citrate
  • Sulfones / administration & dosage*
  • Sulfones / adverse effects
  • Sulfones / pharmacokinetics*
  • Tablets
  • Therapeutic Equivalency
  • Vasodilator Agents / administration & dosage*
  • Vasodilator Agents / adverse effects
  • Vasodilator Agents / pharmacokinetics*


  • Piperazines
  • Purines
  • Sulfones
  • Tablets
  • Vasodilator Agents
  • Sildenafil Citrate