Determination of the Antifungal Agent Voriconazole in Human Plasma Using a Simple Column-Switching High-Performance Liquid Chromatography and Its Application to a Pharmacokinetic Study

Abstract

Voriconazole, (2R,3S)-2-(2,4-difluorophenyl)-3-(5-fluoropyrimidin-4-yl)-1-(1,2,4-triazol-1-yl)butan-2-ol, is a widespectrum triazole antifungal agent (Fig. 1a). It selectively inhibits cytochrome P450 (CYP) dependent 14a-demethylase, which is a key enzyme in the fungal sterol biosynthesis pathway, specifically the conversion of lanosterol to ergosterol within the membrane component. Compared with other azole compounds, voriconazole shows a broader-spectrum antifungal activity, and it therefore can be used to treat severe or serious fungal infections, e.g., Candida spp., Aspergillus spp., Cryptococcus spp.2-4) Voriconazole is metabolized hepatically, primarily via the CYP isoenzymes CYP2C9, CYP2C19 and CYP 3A4. 4,5) The metabolites of voriconazole do not have antifungal activity. The CYP2C19 isozyme, which acts in the major metabolic pathway for voriconazole, exhibits significant genetic polymorphism, and consequently a number of poor metabolizers (PMs) are found. Potent interactions with voriconazole by CYP isozymes also affect the plasma levels of voriconazole. 5,6) The PMs are found with much higher frequency (18 to 23%) in the Japanese population than in North American and European white populations (3 to 5%). 7,8) Since the PMs result in increased plasma levels of voriconazole, 5,6) it is important to determine the concentration of voriconazole in human plasma to avoid side effects of voriconazole treatment, such as photopsia, skin rashes, liver dysfunction and so on. Studies concerning the safety, tolerability and pharmacokinetics of intravenous and/or oral dosing regimens of voriconazole demonstrated that voriconazole was generally safe and well tolerated, and it exhibited nonlinear pharmacokinetics. 9,10) Therapeutic monitoring of voriconazole in plasma, therefore, might be warranted in some patients who are at higher risk, especially due to PMs of the CYP2C19 genotype.Several methods including high-performance liquid chromatography (HPLC) combined with mass spectrometry, 11) or with UV detection, [12][13][14][15][16] and bioassay, 16) have been reported to determine voriconazole in biological fluids. The previously reported HPLC-UV methods are clinically useful, but sample pretreatment methods such as solid phase extraction 13) or a solvent extraction 15,16) followed by evaporation under nitrogen stream are required for the assay. Such tedious procedures are undesirable for many clinical applications, whereas an on-line HPLC method with direct plasma injection would be much more convenient. Therefore, there have been developed two methods; one is size exclusion chromatography coupled with a reversed-phase HPLC system with column-switching, 12) and another is a direct plasma injection HPLC micro method using an internal surface reversed-phase column. 14)In this paper, we describe a simple column-switching HPLC system with a direct plasma injection that does not involve any complicated pretreatment. We have used this system to study the pharmacokinetics of voriconazole in healthy volunteers following a sin...

Development, Validation, and Routine Application of a High-Performance Liquid Chromatography Method Coupled with a Single Mass Detector for Quantification of Itraconazole, Voriconazole, and Posaconazole in Human Plasma

“…Antifungal therapeutic drug monitoring (TDM) could be an important tool in clinical practice if compliance is poor, the therapeutic window is narrow, or drug interactions and toxicity are common adverse effects. Therefore, quantification of drug in plasma samples is an important issue in clinical practice to improve efficacy and to decrease toxicity.Many methods to individually quantify ITZ (6,7,9,17,18,26,[31][32][33][34]37,45,46), PSC (8,35,39), and VRC (11,20,24,25,28,29,36,38) in human plasma have been published. Only one method described the quantification of the three triazoles plus fluconazole, ITC metabolite, and ketokonazole in human plasma using a solid-phase extraction procedure.…”

“…Many methods to individually quantify ITZ (6, 7, 9, 17, 18, 26, 31-34, 37, 45, 46), PSC (8,35,39), and VRC (11,20,24,25,28,29,36,38) in human plasma have been published. Only one method described the quantification of the three triazoles plus fluconazole, ITC metabolite, and ketokonazole in human plasma using a solid-phase extraction procedure.…”

A New HPLC Validated Method for Therapeutic Monitoring Of Triazoles in Human Plasma: First Results in Leukaemic Patients

“…Several reported the use of high performance liquid chromatography coupled with ultraviolet determination (HPLC-UV) [4,[13][14][15][16][17][18][19][20][21][22][23][24]. More recently, liquid chromatographic methods based on mass spectrometry (LC-MS/MS) detection have been developed to this purpose [25][26][27][28][29][30][31][32], although MS facilities are not always available in standard hospital laboratories, because they are expensive compared with a simple HPLC system.…”

Therapeutic Drug Monitoring of Voriconazole in Children

“…24 The methods employed included agar well diffusion bioassays 25 and high-performance liquid chromatography (HPLC) with fluorescence, mass spectrometric (MS), or ultraviolet (UV) detection. 12,15,19,20,[25][26][27][28][29][30][31][32][33][34][35][36][37] These have recently been reviewed. 22,38 Briefly, bioassays are simple and inexpensive to perform compared with HPLC.…”

“…22,40 HPLC-UV methods are common and robust, but may be plagued with complicated sample pretreatment methods. 31 This can be avoided by using column-switching HPLC methods with direct plasma injection. 31 For children, liquid chromatography-MS/MS methods are attractive because they can accept small sample sizes (less than 10 mL).…”