Development and validation of an enantioselective LC-MS/MS method for the analysis of the anthelmintic drug praziquantel and its main metabolite in human plasma, blood and dried blood spots.

Praziquantel (PZQ) is the treatment of choice against various trematode and cestode infections. To study the pharmacokinetics of PZQ in patients infected with the liver fluke Opisthorchis viverrini, we developed and validated an enantioselective liquid chromatography coupled to tandem mass spectrometry method for the analysis of R - and S -PZQ and its R -trans-4-OH-PZQ metabolite in human plasma, blood and dried blood spots (DBS). The analytes were detected in the positive mode using selected reaction monitoring (R- and S-PZQ: m/z 312.2 → 202.2; R-trans -4-OH-PZQ: m/z 328.0 → 202.0). Prior to the chiral separation with a cellulose tris(3-chloro-4-methylphenylcarbamate) column, the analytes were purified from matrix contaminants and concentrated on a C-18 trapping column. The analytical range for each PZQ enantiomer was 0.01-2.5 μg/mL, and 0.1-25 μg/mL for the metabolite. The method met the requirements regarding precision (± 15%, ± 20% at the lower limit of quantification-LLOQ), intra- and inter-assay accuracy (85-115%, 80-120% at LLOQ), and linearity (R(2) ≥ 0.998). The analytes were stable in stock solutions as well as in plasma, blood and DBS. For DBS, the influences of hematocrit and blood spot size were considered as minor. Our validation results show that the method presented here is precise, accurate and selective, and can be used for pharmacokinetic studies. Moreover, the enantioselective separation was achieved with a run time of 11.5 min and a simple sample processing method.