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.