title: Simultaneous determination of sildenafil citrate and some nitric oxide releasing drugs in human plasma using UPLC MS/MS.
abstract: OBJECTIVE
  The inadvertent combination of sildenafil (SLD) and nitric oxide releasing compounds (NRC) may cause a life threatening hypotension and conversion of coital angina into an irreversible one. The aim of this study was to develop and validate a UPLC MS/MS method for the simultaneous quantitative analysis of SLD, nicorandil (NRD), and ARG in human plasma to determine the safety margins for drug combinations.
  
  
  METHODS
  Chromatographic elution was achieved in 4min using gradient elution and an injection volume of 10μL. Electro-spray positive ionization (ESI+ve) detection and multiple-reaction monitoring mode (MRM) were used for detection.
  
  
  RESULTS
  The method was found to be linear (10-900ng/mL for SLD and NRD while 1-30μg/mL for ARG), accurate and precise (99.35±1.58, 99.62±1.13, and 100.04±1.22% for SLD, NRD and ARG; respectively) and met all other validation requirements.
  
  
  CONCLUSIONS
  The developed UPLC MS/MS method is suitable for fast, sensitive, accurate and simultaneous determinations of SLD, NRD, and ARG in plasma.
authors.affiliation: Pharmaceutical Chemistry Department, Faculty of Pharmacy, Cairo University, Cairo, Egypt.
authors.forename: Ramzia
authors.initials: R
authors.lastname: El-Bagary
authors.affiliation: Department of Chemistry, School of Sciences & Engineering, The American University in Cairo, AUC Ave, PO Box 74, New Cairo 11835, Egypt. Electronic address: hazzazy@aucegypt.edu.
authors.forename: Hassan M E
authors.initials: HM
authors.lastname: Azzazy
authors.affiliation: Pharmaceutical Chemistry Department, Faculty of Pharmacy, Cairo University, Cairo, Egypt.
authors.forename: Ehab F
authors.initials: EF
authors.lastname: ElKady
authors.affiliation: Pharmaceutical Chemistry Department, Faculty of Pharmacy, Ahram Canadian University, 6th October City, Egypt.
authors.forename: Faten
authors.initials: F
authors.lastname: Farouk
mesh_terms: D002851:Chromatography, High Pressure Liquid; D004347:Drug Interactions; D006801:Humans; D020108:Nicorandil / Q000737:chemistry; D009569:Nitric Oxide / Q000737:chemistry*; D010879:Piperazines / Q000737:chemistry*; D011687:Purines / Q000737:chemistry; D015203:Reproducibility of Results; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000737:chemistry*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D010879:Piperazines; D011687:Purines; D013450:Sulfones; D020108:Nicorandil; D009569:Nitric Oxide; D000068677:Sildenafil Citrate
keywords: Drug interactions; LC–MS/MS; Nicorandil; Sildenafil citrate; l-Arginine