title: Development and validation of an ultra performance liquid chromatography tandem mass method for sildenafil and N-desmethyl sildenafil plasma determination and quantification.
abstract: Sildenafil is a selective inhibitor of cGMP-specific type 5 phosphodiesterase (PDE5) used for the treatment of masculine erectile dysfunction and Pulmonary Arterial Hypertension (PAH). Sildenafil causes vasodilatation; relax of the smooth muscle and reduction of pulmonary arterial pressure. In the liver cytocrome P450 metabolizes sildenafil into its active metabolite, N-desmethyl sildenafil. The determination of plasma levels of sildenafil and N-desmethyl sildenafil could be useful for therapy optimization and pharmacokinetic studies. We have developed and validated a new method for the quantification of sildenafil and its metabolite in human plasma by rapid protein precipitation extraction, using an UPLC system, coupled with a tandem mass spectrometric detector (UPLC-MS/MS). The calibration range was fitted at least square model (r(2)≥0.999), with an accuracy and an intra- and inter-day RSD% (Relative Standard Deviation), both for sildenafil and N-desmethyl sildenafil, lower than 15%, as required by the FDA guidelines; LLOQ, LLOD, ULOQ were 3.9ng/mL, 1.95ng/mL and 1000ng/mL, respectively, for both analytes. Matrix effect, expressed as mean percent deviation of peak areas, was in the range between 2.6% and 5.8%, lower than 15% as required by guidelines. The mean recovery was 83.2 % for sildenafil and 84.5% for N-desmethyl sildenafil. This method has successfully been applied to a clinical pharmacokinetic study of sildenafil and N-desmethyl sildenafil in patients with PAH undergoing cardiac surgery.
authors.affiliation: Unit of Infectious Diseases, University of Turin, Department of Medical Sciences, Amedeo di Savoia Hospital, (#Laboratory of Clinical Pharmacology and Pharmacogenetic), Turin, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Simiele
authors.affiliation: Unit of Infectious Diseases, University of Turin, Department of Medical Sciences, Amedeo di Savoia Hospital, (#Laboratory of Clinical Pharmacology and Pharmacogenetic), Turin, Italy. Electronic address: debora.pensi@unito.it.
authors.forename: Debora
authors.initials: D
authors.lastname: Pensi
authors.affiliation: Department of Anesthesia and Critical Care Medicine, University of Turin, Città della Salute e della Scienza Hospital, Turin, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Pasero
authors.affiliation: Department of Anesthesia and Critical Care Medicine, University of Turin, Città della Salute e della Scienza Hospital, Turin, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Ivaldi
authors.affiliation: Department of Anesthesia and Critical Care Medicine, University of Turin, Città della Salute e della Scienza Hospital, Turin, Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: Rinaldi
authors.affiliation: Unit of Infectious Diseases, University of Turin, Department of Medical Sciences, Amedeo di Savoia Hospital, (#Laboratory of Clinical Pharmacology and Pharmacogenetic), Turin, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Di Perri
authors.affiliation: Department of Anesthesia and Critical Care Medicine, University of Turin, Città della Salute e della Scienza Hospital, Turin, Italy.
authors.forename: Vito Marco
authors.initials: VM
authors.lastname: Ranieri
authors.affiliation: Unit of Infectious Diseases, University of Turin, Department of Medical Sciences, Amedeo di Savoia Hospital, (#Laboratory of Clinical Pharmacology and Pharmacogenetic), Turin, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: D'Avolio
mesh_terms: D002853:Chromatography, Liquid / Q000379:methods*; D006801:Humans; D057230:Limit of Detection; D058986:Phosphodiesterase 5 Inhibitors / Q000097:blood*; D015203:Reproducibility of Results; D000068677:Sildenafil Citrate / Q000097:blood*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D058986:Phosphodiesterase 5 Inhibitors; D000068677:Sildenafil Citrate
keywords: Metabolite; N-desmethyl sildenafil; Sildenafil; Therapeutic drug monitoring; Ultra performance liquid chromatography tandem mass