Quantification of voriconazole in plasma by liquid chromatography-tandem mass spectrometry

A convenient liquid chromatography-tandem mass spectrometry method for the quantification of the triazole antifungal agent voriconazole in plasma samples is described. Fenbuconazole is used as an internal standard. After protein precipitation, automated solid-phase extraction is applied. Electrospray ionization in the positive mode is used and the following mass transitions are recorded: voriconazole, 350 -> 127; and fenbuconazol, 337 -> 125. The analytical run time is 4 min. The response was linear from 78 to 5000 mu g/L. The total coefficient of variation (n=16) was 12.6% for a low-concentration pool (143 mu g/L), 4.7% for a medium-concentration pool (419 mu g/L), and 5.0% for a high-concentration pool (4304 mu g/L). The method is proposed for future investigations that should be performed to test the hypothesis that therapeutic drug monitoring of voriconazole is clinically useful

An on-line solid phase extraction procedure for the routine quantification of caspofungin by liquid chromatography-tandem mass spectrometry

Background: Extensive sets of data are required to investigate the potential use of a therapeutic drug monitoring with individualization of dosage of the antimycotic compound caspofungin. The goal was to develop an improved liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for this aim. Methods: Following protein precipitation, on-line solid phase extraction was performed for sample preparation. As the internal standard compound the veterinary drug tylosin was used. A standard validation protocol was applied. Results: Good reproducibility and accuracy of the method were observed. On-line solid phase extraction resulted in a convenient work-flow and good robustness of the method. Conclusions: This improved LC-MS/MS method was found reliable and convenient. It can be suggested for further work on the clinical pharmacology of caspofungin in the setting of clinical research laboratories

Role of therapeutic drug monitoring in pulmonary infections : use and potential for expanded use of dried blood spot samples

Respiratory tract infections are among the most common infections in men. We reviewed literature to document their pharmacological treatments, and the extent to which therapeutic drug monitoring (TDM) is needed during treatment. We subsequently examined potential use of dried blood spots as sample procedure for TDM. TDM was found to be an important component of clinical care for many (but not all) pulmonary infections. For gentamicin, linezolid, voriconazole and posaconazole dried blood spot methods and their use in TDM were already evident in literature. For glycopeptides, beta-lactam antibiotics and fluoroquinolones it was determined that development of a dried blood spot (DBS) method could be useful. This review identifies specific antibiotics for which development of DBS methods could support the optimization of treatment of pulmonary infections

Impact of glucuronide interferences on therapeutic drug monitoring of posaconazole by tandem mass spectrometry

Background: Posaconazole is a novel antifungal drug for oral application intended especially for therapy of invasive mycoses. Due to variable gastrointestinal absorption, adverse side effects, and suspected drug-drug interactions, therapeutic drug monitoring (TDM) of posaconazole is recommended. Method: A fast ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for quantification of posaconazole with a run-time <3 min was developed and compared to a LC-MS/MS method and HPLC method with fluorescence detection. Results: During evaluation of UPLC-MS/MS, two earlier eluting peaks were observed in the MRM trace of posaconazole. This was only seen in patient samples, but not in spiked calibrator samples. Comparison with LC-MS/MS disclosed a significant bias with higher concentrations measured by LC-MS/MS, while UPLC-MS/MS showed excellent agreement with the commercially available HPLC method. In the LC-MS/MS procedure, comparably wide and left side shifted peaks were noticed. This could be ascribed to in-source fragmentation of conjugate metabolites during electrospray ionisation. Precursor and product ion scans confirmed the assumption that the additional compounds are posaconazole glucuronides. Reducing the cone voltage led to disappearance of the glucuronide peaks. Slight modification of the LC-MS/MS method enabled separation of the main interference, leading to significantly reduced deviation. Conclusions: These results highlight the necessity to reliably eliminate interference from labile drug metabolites for correct TDM results, either by sufficient separation or selective MS conditions. The presented UPLC-MS/MS method provides a reliable and fast assay for TDM of posaconazole. Clin Chem Lab Med 2010; 48:1723-31

A Comparative Study of Newly Developed HPLC-DAD and UHPLC-UV Assays for the Determination of Posaconazole in Bulk Powder and Suspension Dosage Form

Objective. To develop and compare HPLC-DAD and UHPLC-UV assays for the quantitation of posaconazole in bulk powder and suspension dosage form. Methods. Posaconazole linearity range was 5–50 μg/mL for both assays. For HPLC-DAD assay, samples were injected through Zorbax SB-C18 (4.6 × 250 mm, 5 μm) column. The gradient elution composed of the mobile phase acetonitrile: 15 mM potassium dihydrogen orthophosphate (30 : 70 to 80 : 20, linear over 7 minutes) pumped at 1.5 mL/min. For UHPLC-UV assay, samples were injected through Kinetex-C18 (2.1 × 50 mm, 1.3 μm) column. The mobile phase composed of acetonitrile: 15 mM potassium dihydrogen orthophosphate (45 : 55) pumped isocratically at 0.4 mL/min. Detection wavelength was 262 nm in both methods. Results. The run time was 11 and 3 minutes for HPLC-DAD and UHPLC-UV assays, respectively. Both assays were linear (r2>0.999) with CV% and % error of the mean <3%. Limits of detection and quantitation were 0.82 and 2.73 μg/mL for HPLC-DAD and 1.04 and 3.16 μg/mL for UHPLC-UV, respectively. The methods quantitated PSZ in suspension dosage form with no observable interferences. Conclusions. Both assays were proven sensitive and selective according to ICH guidelines. UHPLC-UV assay exhibited some economic and chromatographic separation superiority

High Performance Liquid Chromatographic Assay for the Simultaneous Determination of Posaconazole and Vincristine in Rat Plasma

Purpose. Developing a validated HPLC-DAD method for simultaneous determination of posaconazole (PSZ) and vincristine (VCR) in rat plasma. Methods. PSZ, VCR, and itraconazole (ITZ) were extracted from 200 μL plasma using diethyl ether in the presence of 0.1 M sodium hydroxide solution. The organic layer was evaporated in vacuo and dried residue was reconstituted and injected through HC-C18 (4.6 × 250 mm, 5 μm) column. In the mobile phase, acetonitrile and 0.015 M potassium dihydrogen orthophosphate (30 : 70 to 80 : 20, linear gradient over 7 minutes) pumped at 1.5 mL/min. VCR and PSZ were measured at 220 and 262 nm, respectively. Two Sprague Dawley rats were orally dosed PSZ followed by iv dosing of VCR and serial blood sampling was performed. Results. VCR, PSZ, and ITZ were successfully separated within 11 min. Calibration curves were linear over the range of 50–5000 ng/mL for both drugs. The CV% and % error of the mean were ≤18% and limit of quantitation was 50 ng/mL for both drugs. Rat plasma concentrations of PSZ and VCR were simultaneously measured up to 72 h and their calculated pharmacokinetics parameters were comparable to the literature. Conclusion. The assay was validated as per ICH guidelines and is appropriate for pharmacokinetics drug-drug interaction studies

Implementation of Isavuconazole in a Fluorescence-Based High-Performance Liquid Chromatography Kit Allowing Simultaneous Detection of All Four Currently Licensed Mold-Active Triazoles

ABSTRACT Isavuconazole (ISZ) is a newly available broad-spectrum triazole agent recently approved for the treatment of both invasive aspergillosis and mucormycosis. The aim of this study was to develop a simple and reliable method for therapeutic drug monitoring (TDM) of ISZ in human plasma samples. The method involves using a kit from ChromSystems intended for TDM of itraconazole (ITZ), posaconazole (PSZ), and voriconazole (VRZ) in serum/plasma for sample preparation and high-performance liquid chromatography, using fluorescence detection with emission and excitation wavelengths set to 261 and 366 nm, respectively. The assay was linear over the ISZ concentration range of 0.2 to 20.0 mg/liter, using a 0.1-ml sample volume. The inter- and intraday coefficients of variation were all below 3.7%, whereas the accuracies ranged from 95.0 to 106.2% and the mean extraction recovery was 91.9%. In addition, the method worked well using four different Vacutainer types, with six different healthy volunteers and under a number of relevant storage conditions. Finally, the ISZ detection could be seamlessly implemented in the TDM kit for VRZ, PSZ, and ITZ, enabling simultaneous detection of all four triazoles. This method proved to be simple, accurate, precise, and well suited for routine analysis work. It has been implemented in our laboratory for the simultaneous quantitative analysis of ISZ, VRZ, PSZ, and ITZ for TDM and pharmacokinetic research. IMPORTANCE Isavuconazole is a new broad-spectrum triazole agent recently approved for the treatment of both invasive aspergillosis and mucormycosis. Currently, there is no consensus regarding the potential need for TDM of isavuconazole, and no therapeutic window has been defined. However, at the ECIL-6 meeting in 2015, it was advised that TDM is indicated in a number of different settings. In this study, we describe a rapid and validated isocratic HPLC method for fluorescence-based detection and quantification of isavuconazole in human plasma/serum samples. The method is simple and efficient with good accuracy and precision and importantly only requires a small volume of patient plasma/serum. Furthermore, this method is highly sensitive and selective and can be detected simultaneously with the three other triazoles, itraconazole, voriconazole, and posaconazole, without the need for expensive mass spectrometry equipment