title: Validation of a High-Performance Liquid Chromatography-Tandem Mass Spectrometry Method for the Determination of Perhexiline and Cis-Hydroxy-Perhexiline Plasma Concentrations.
abstract: BACKGROUND
  The polymorphic nature of cytochrome P450 2D6 has made therapeutic drug monitoring of the anti-anginal agent perhexiline a compulsory step in reducing adverse events associated with plasma concentrations above the therapeutic range (0.15-0.60 mg/L). The aim of this study was to develop a high-performance liquid chromatography-mass spectrometry/mass spectrometry method for the determination of plasma perhexiline concentrations and its major metabolite cis-hydroxy-perhexiline to reduce sample extraction procedures and improve sample turnaround times.
  
  
  METHODS
  The method was validated by determining the precision and accuracy of calibrators and quality control material, comparing quality assurance program samples and patient samples measured by a previously reported liquid-liquid extraction fluorescence (FL) detection high-performance liquid chromatography method and performing matrix effects investigations.
  
  
  RESULTS
  Replicates of calibrators at concentrations of 3.00 and 0.05 mg/L demonstrated imprecision of <10.8% and inaccuracy of <8.2% for perhexiline and <10.1% and <4.5% for cis-hydroxy-perhexiline, respectively. All samples measured by the 2 methods (n = 102) demonstrated Deming regression of perhexiline = 1.20 FL + 0.00 (Sy.x = 0.08, 1/slope = 0.67); cis-hydroxy-perhexiline = 1.48 FL - 0.20 (Sy.x = 0.40, 1/slope = 0.67).
  
  
  CONCLUSIONS
  The assay performance was deemed acceptable and integrated into the routine therapeutic drug monitoring program of the department.
authors.affiliation: *Department of Clinical Pharmacology, Basil Hetzel Institute, The Queen Elizabeth Hospital, Woodville; †School of Pharmacy and Biomedical Science, University of South Australia; ‡Vascular Diseases and Therapeutics Research Group, Basil Hetzel Institute, The Queen Elizabeth Hospital; and §Discipline of Pharmacology, University of Adelaide, Australia.
authors.forename: Ian S
authors.initials: IS
authors.lastname: Westley
authors.forename: Giovanni
authors.initials: G
authors.lastname: Licari
authors.forename: Benedetta C
authors.initials: BC
authors.lastname: Sallustio
mesh_terms: D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D019389:Cytochrome P-450 CYP2D6 / Q000235:genetics; D016903:Drug Monitoring / Q000379:methods*; D006801:Humans; D059625:Liquid-Liquid Extraction; D010480:Perhexiline / Q000031:analogs & derivatives* / Q000097:blood; D011110:Polymorphism, Genetic; D015203:Reproducibility of Results; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: C493998:hydroxyperhexiline; D019389:Cytochrome P-450 CYP2D6; D010480:Perhexiline