title: Bioequivalence study of two tablet formulations of sildenafil.
abstract: 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.
authors.affiliation: Medical Department, Grupo Tecnimede, Prior Velho, Portugal. dmed.ct.tecnimede@mail.telepac.pt
authors.forename: Ana Cristina Franco
authors.initials: AC
authors.lastname: Spínola
authors.forename: Susana
authors.initials: S
authors.lastname: Almeida
authors.forename: Augusto
authors.initials: A
authors.lastname: Filipe
authors.forename: Mario
authors.initials: M
authors.lastname: Tanguay
authors.forename: Mercedes
authors.initials: M
authors.lastname: Yritia
mesh_terms: D000293:Adolescent; D000328:Adult; D019540:Area Under Curve; D002626:Chemistry, Pharmaceutical; D018592:Cross-Over Studies; D006801:Humans; D008297:Male; D010879:Piperazines / Q000008:administration & dosage* / Q000009:adverse effects / Q000493:pharmacokinetics*; D011687:Purines / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000008:administration & dosage* / Q000009:adverse effects / Q000493:pharmacokinetics*; D013607:Tablets; D013810:Therapeutic Equivalency; D014665:Vasodilator Agents / Q000008:administration & dosage* / Q000009:adverse effects / Q000493:pharmacokinetics*
chemical_list: D010879:Piperazines; D011687:Purines; D013450:Sulfones; D013607:Tablets; D014665:Vasodilator Agents; D000068677:Sildenafil Citrate