Enzymatic tumour tissue digestion coupled to SPE-UPLC-Tandem Mass Spectrometry as a tool to explore paclitaxel tumour penetration.

Paclitaxel is a good compound for regional (intraperitoneal) chemotherapy of peritoneal carcinomatosis. During IPEC, a cytotoxic solution is circulated in the peritoneal cavity, thereby promoting close contact between the cytotoxic agent and the exposed (residual) tumour tissue. To further explore the role of PTX in this type of treatment and study the impact of treatment modalities on tumour tissue penetration, in-vivo animal experiments were set-up. In literature, PTX tumour uptake is frequently studied using autoradiography and/or fluorescence microscopy techniques. Owing to their semi-quantitative nature on one hand and the difficulty of incorporating imaging data within a pharmacokinetic-pharmacodynamic modelling framework on the other hand, we set out to develop a validated assay for the quantification of PTX in tumour tissue samples. Furthermore, in order to maximise spatial resolution, care was taken to minimise the sample weight necessary for the analysis. Based on an enzymatic tumour tissue digestion protocol, an easy, less labour-intensive, when compared to mechanical tissue disruption techniques, method was developed. Through validation experiments we showed that our method reliably quantifies PTX in a working range of 30-8000 ng/g tumour tissue. Finally, using samples from the in-vivo experiments we demonstrated the suitability of the developed method.

Simultaneous quantitative analysis of the antimalarials pyrimethamine and sulfamethoxypyrazine in plasma samples using liquid chromatography/tandem mass spectrometry.

The work presented here deals with the development of a quantitative tool for the simultaneous determination of sulfamethoxypyrazine (sulfalene)/pyrimethamine in plasma. The chromatography used only takes 12.5 min, allowing a fast sample turnover time. Relative standard deviation of retention times was never above 3.48% (n = 66). Adequate sample clean-up was achieved by a simple and relatively fast liquid/liquid extraction. In this way, ionisation suppression effects, typical for more simple sample clean-up procedures, could be avoided resulting in absolute plasma effects of maximum -17.1% for sulfalene, -16.1 for the internal standard (IS), and 12% for pyrimethamine. For both pyrimethamine and sulfalene, quadratic calibration curves from 0.00101 to 0.807 microg/mL for pyrimethamine and from 0.271 to 216 microg/mL for sulfalene gave the best fit. Mean coefficients of determination (R2) were 0.9951 (n = 6, CV% 0.39) for pyrimethamine and 0.9942 (n = 6, CV% 0.13) for sulfalene. Precision was below 9.35% for pyrimethamine and 13.9% for sulfalene. Inaccuracy remained below 15% at all cases. The optimised method was used for a time-course study of the sulfalene/pyrimethamine combination concentration in plasma of patients treated with Co-Arinate, a new curative antimalaria-medicine.