title: Cyproterone acetate quantification in human plasma by high-performance liquid chromatography coupled to atmospheric pressure photoionization tandem mass spectrometry. Application to a comparative pharmacokinetics study.
abstract: A specific, fast and sensitive high performance liquid chromatography (HPLC) coupled to atmospheric pressure photoionization (APPI) tandem mass spectrometric (LC-MS/MS) assay was developed for the determination of cyproterone (CYP) acetate (CAS 427-51-0) in human plasma. The retention times were 3.26 and 2.90 min for CYP acetate and its internal standard (I. S.) finasteride (FIN), respectively. The overall mean recovery, using liquid/liquid extraction, was found to be 109.0, 107.7 and 100.3%, for low, medium and high concentrations, respectively. Calibration curves were linear in the concentration range of 0.1-50.0 ng/ml, and the lower limit of quantification (LLOQ) was 0.1 ng/ml. The LLOQ, 0.1 ng/ml, was sensitive enough for detecting terminal phase concentrations of the drug. Inter-batch precision of the method ranged from 2.2 to 5.55%, while Inter-batch accuracy ranged from 95.5 to 100.0%. Intra-batch precision ranged from 1.8 to 5.6%, while Intra-batch accuracy ranged from 92.0 to 99.4% at concentrations of 0.3 ng/ml, 20.0 and 40.0 ng/ml. The developed method was applied to a bioequivalenc study of CYP acetate in a group of 44 female volunteers at a single oral dose of a 2 mg tablet, in a combination of ethinylestradiol/CYP acetate (0.25/2 mg). The plasma concentration of CYP acetate did not differ significantly after administration of both formulations (test formulation and the reference one). The geometric mean and respective 90% CI of CYP acetate test/reference percent ratios were 90.66% (84.39-97.40%) for Cmax and 96.20% (90.45-102.33%) for AUC0-t.
authors.affiliation: Synchrophar Assessoria e Desenvolvimento de Projetos Clínicos S/S Ltda., Campinas, SP, Brazil. medney@synchrophar.com
authors.forename: Ney Carter
authors.initials: NC
authors.lastname: Borges
authors.forename: Ana
authors.initials: A
authors.lastname: Mazuqueli
authors.forename: Ronilson Agnaldo
authors.initials: RA
authors.lastname: Moreno
authors.forename: Rafael Barrientos
authors.initials: RB
authors.lastname: Astigarraga
authors.forename: Carlos Eduardo
authors.initials: CE
authors.lastname: Sverdloff
authors.forename: Paulo Alexandre Rebelo
authors.initials: PA
authors.lastname: Galvinas
authors.forename: Maurício Rocha de Magalhães
authors.initials: MR
authors.lastname: Sampaio
authors.forename: Washington Moreira
authors.initials: WM
authors.lastname: da Silva
mesh_terms: D000328:Adult; D000726:Androgen Antagonists / Q000097:blood* / Q000493:pharmacokinetics; D019540:Area Under Curve; D002851:Chromatography, High Pressure Liquid; D018592:Cross-Over Studies; D017373:Cyproterone Acetate / Q000097:blood* / Q000493:pharmacokinetics; D004311:Double-Blind Method; D005260:Female; D005615:Freezing; D006801:Humans; D008875:Middle Aged; D011786:Quality Control; D012015:Reference Standards; D015203:Reproducibility of Results; D012996:Solutions; D013048:Specimen Handling; D053719:Tandem Mass Spectrometry; D055815:Young Adult
chemical_list: D000726:Androgen Antagonists; D012996:Solutions; D017373:Cyproterone Acetate