Determination of the antifungal agent posaconazole in human serum by HPLC with parallel column-switching technique

Posaconazole is a new broad-spectrum antifungal agent that is currently only available as an oral suspension and shows high intra- and inter-individual differences in oral bioavailibility. Pre-existing methods for the determination of the substance involve the use of internal standards or require a quite complicated and time-consuming sample pre-treatment. Our HPLC method is fast and fully-automated and there is no need for any manual sample pre-treatment. On-line transfer of posaconazole from the extraction column was followed by chromatographic separation on a C18 column and fluorescence detection (lambda(ex): 261 nm, lambda(em): 357 nm). Retention time of posaconazole was about 11.7 min, the lower limit of quantification was found to be 0.1 mg/l. A linear calibration curve was obtained over the concentration range of 0.1-5 mg/l using a 50 microl sample (r(2)=0.999). The relative standard deviations of intra-day variations ranged from 2.3% to 9.4%, intra-day accuracy from 88.8% to 114.8%.