Practice of solid-phase extraction and protein precipitation in the 96-wel format combined with high-performance liquid chromatography-ultraviolet detection for the analysis of drugs in plasma and brain

摘要

C_(l8) Empore 96-well extraction disc plates have been employed for the analysis of three drugs with different polarities in plasma in conjunction with HPLC-UV; rufinamide, ICL670 and an anticonvulsant agent (AAl) in an early stage of development. With the most polar compound (AA1), ion-pair extraction at pH 12 was applied. The method developed for the assay of AAl in plasma was applied to its detennination in brain using an Oasis HLB plate following homogenisation in a pH 7.4 buffer and protein precipitation with NaOH-ZnSO_4, thereby saving time for method development. Protein precipitation in the 96-well fonnat with filtration of the precipitate was applied to the detennination of ICL670, a highly protein-bound compound (>99.5%), with a go~d recovery (78%). Reversed-phase chromatography was applied using a short 5 cm column packed with 3 f1m particles for the detennination of ICL670 and AAl and two parallel columns (15 cm long) for the determination of rufinamide. The methods were used routinely, one plate per analysis day being processed, resulting in increase in sample throughput and saving in solvents.