title: Propylthiouracil quantification in human plasma by high-performance liquid chromatography coupled with electrospray tandem mass spectrometry: application in a bioequivalence study.
abstract: A rapid, sensitive and specific method for quantifying propylthiouracil in human plasma using methylthiouracil as the internal standard (IS) is described. The analyte and the IS were extracted from plasma by liquid-liquid extraction using an organic solvent (ethyl acetate). The extracts were analyzed by high performance liquid chromatography coupled with electrospray tandem mass spectrometry (HPLC-MS/MS) in negative mode (ES-). Chromatography was performed using a Phenomenex Gemini C18 5μm analytical column (4.6mm×150mm i.d.) and a mobile phase consisting of methanol/water/acetonitrile (40/40/20, v/v/v)+0.1% of formic acid. For propylthiouracil and I.S., the optimized parameters of the declustering potential, collision energy and collision exit potential were -60 (V), -26 (eV) and -5 (V), respectively. The method had a chromatographic run time of 2.5min and a linear calibration curve over the range 20-5000ng/mL. The limit of quantification was 20ng/mL. The stability tests indicated no significant degradation. This HPLC-MS/MS procedure was used to assess the bioequivalence of two propylthiouracil 100mg tablet formulations in healthy volunteers of both sexes in fasted and fed state. The geometric mean and 90% confidence interval CI of Test/Reference percent ratios were, without and with food, respectively: 109.28% (103.63-115.25%) and 115.60% (109.03-122.58%) for Cmax, 103.31% (100.74-105.96%) and 103.40% (101.03-105.84) for AUClast.
  
  
  CONCLUSIONS
  This method offers advantages over those previously reported, in terms of both a simple liquid-liquid extraction without clean-up procedures, as well as a faster run time (2.5min). The LOQ of 20ng/mL is well suited for pharmacokinetic studies. The assay performance results indicate that the method is precise and accurate enough for the routine determination of the propylthiouracil in human plasma. The test formulation with and without food was bioequivalent to reference formulation. Food administration increased the Tmax and decreased the bioavailability (Cmax and AUC).
authors.affiliation: Department of Surgery, Faculty of Odontology, University of Sao Francisco (USF), Braganca Paulista, SP, Brazil; Department of Surgery, Faculty of Odontology, University Camilo Castelo Branco (UNICASTELO), São Paulo, SP, Brazil; Galeno Research Unit, Latino Coelho St., 1301, Parque Taquaral, 13087-010 Campinas, SP, Brazil. Electronic address: mendesgd@yahoo.com.br.
authors.forename: Gustavo D
authors.initials: GD
authors.lastname: Mendes
authors.affiliation: Galeno Research Unit, Latino Coelho St., 1301, Parque Taquaral, 13087-010 Campinas, SP, Brazil; Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Campinas, SP, Brazil.
authors.forename: Samara
authors.initials: S
authors.lastname: Bittencourt
authors.affiliation: Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Campinas, SP, Brazil.
authors.forename: Celso Francisco Pimentel
authors.initials: CF
authors.lastname: Vespasiano
authors.affiliation: Galeno Research Unit, Latino Coelho St., 1301, Parque Taquaral, 13087-010 Campinas, SP, Brazil.
authors.forename: Tainah
authors.initials: T
authors.lastname: Babadópulos
authors.affiliation: Institute of Biophysics Carlos Chagas Filho/UFRJ, CCS-Bloco G, 21949-900 Rio de Janeiro, RJ, Brazil.
authors.forename: Thiago
authors.initials: T
authors.lastname: Gagliano-Jucá
authors.affiliation: Galeno Research Unit, Latino Coelho St., 1301, Parque Taquaral, 13087-010 Campinas, SP, Brazil.
authors.forename: André Moreira Martins
authors.initials: AM
authors.lastname: Arruda
authors.affiliation: Department of Pharmaceutical and Toxicological Chemistry, Federico II University, Naples, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Perissutti
authors.affiliation: Department of Pharmaceutical and Toxicological Chemistry, Federico II University, Naples, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Frecentese
authors.affiliation: Galeno Research Unit, Latino Coelho St., 1301, Parque Taquaral, 13087-010 Campinas, SP, Brazil; Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Campinas, SP, Brazil; Department of Pharmacology, Institute of Biomedical Sciences, University of Sao Paulo, São Paulo, SP, Brazil.
authors.forename: Gilberto
authors.initials: G
authors.lastname: De Nucci
mesh_terms: D000293:Adolescent; D000328:Adult; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011441:Propylthiouracil / Q000097:blood* / Q000737:chemistry / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D053719:Tandem Mass Spectrometry / Q000379:methods*; D013810:Therapeutic Equivalency; D055815:Young Adult
chemical_list: D011441:Propylthiouracil
keywords: Bioavailability; Healthy volunteer; Pharmacokinetics