Antimycotics are a group of drugs used to treat fungal infections. There are currently 4 main types of antifungal drugs: polyenes, flucytosine, azoles and echinocandins. In this master's thesis, we focused on 8 representatives: flucytosine, fluconazole, voriconazole, ketoconazole, isavuconazole, posaconazole, hydroxyitraconazole and itraconazole. Due to the large pharmacokinetic variability, serious toxic effects at higher doses and possible interactions with other drugs, it is desirable to monitor the concentration of some antimycotics. The purpose of monitoring the concentration of drugs in patients’ blood is to check whether it is within the recommended values. This can prevent toxic effects or make sure the dose is high enough for successful treatment. The reference method for determining the concentration of drugs in serum is liquid chromatography coupled with mass spectrometry. Due to its high selectivity, robustness and relatively low influence of interferences, this analytical method is the gold standard for drug concentration monitoring in clinical laboratories. Our task was to validate whether the method of liquid chromatography coupled with tandem mass spectrometry is suitable for routine use in determining the concentration of 8 antimycotics in serum. The validation process proved the accuracy (bias <14,0 %), precision (CV <5,5 %) and selectivity of the method. We determined the linear range (deviation from linearity <10,4 %) and the limit of detection and quantification for each analyte (CV <11,6 %, bias <10,0 %). We demonstrated adequate stability of samples stored at different temperatures after 8 days for posaconazole and itraconazole, and after 15 days for the remaining 6 analytes (difference from fresh sample <15,0 %). We checked for presence of small amounts of analytes remaining in the system and their influence on blank sample measurements (<17,3 % of peak area at limit of quantification). We also checked the matrix effect for 4 antimycotics (ME >100 % for isavuconazole, voriconazole and fluconazole, ME <100 % for posaconazole) on the measured concentration or peak area. We demonstrated successful compensation of the matrix effect at higher concentrations, using the peak area ratio of the analyte and its internal standard. After successful validation, we concluded that the method meets the standards and is suitable for use for routine purposes.
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