Therapeutic drug monitoring of voriconazole: validation of a high performance liquid chromatography method and comparison with an ARK immunoassay

Abstract

Objective Voriconazole is an antifungal agent used in the treatment of aspergillosis and fluconazole-resistant Candida infections. Therapeutic drug monitoring (TDM) of voriconazole is recommended to optimise clinical results. The aim of this study was the development and validation of a high performance liquid chromatography (HPLC) method for measuring voriconazole in human serum, and comparison with an ARK immunoassay method. Methods Linearity, precision, accuracy and stability of the HPLC method were validated according to the US Food and Drug Administration (FDA) and European Medicines Agency (EMA) guidelines. The method was applied to the analysis of 58 trough serum samples from patients treated with voriconazole, and the HPLC-UV (ultraviolet) method was compared with an ARK immunoassay. The correlation of both methods was studied by the Pearson regression coefficient and the concordance of the values was evaluated by the Bland-Altman and Passing-Bablok methods. Results All validation parameters met the criteria set out in the FDA and EMA guidelines. The standard curve was linear over a concentration range of 0.25–16 µg/mL with a limit of quantification of 0.125 µg/mL. No interactions between voriconazole and other drugs was observed and voriconazole was stable after 1 month at −80°C. Comparison of the HPLC method and the enzyme immunoassay method showed a linear correlation with a systematic error of −0.61 µg/mL between both methods. Conclusion The method developed is simple and fast and can be easily applied for routine therapeutic drug monitoring of voriconazole. The HPLC-UV method was more sensitive than the immunoassay method and there was concordance with the immunoassay. Consequently both methods could be used, considering the correlation between them.