Dynamic cation-exchange systems for the separation of drugs derived from butyrophenone and diphenylpiperidine by high-performance liquid chromatography and applied in the determination of halopemide in plasma.

Dynamic (solvent generated) cation-exchange systems for the separation of drugs and main metabolites derived from butyrophenone and diphenylpiperidine (haloperidol, pimozide, halopemide) were investigated. The effect of organic modifier, detergent, counter-ion concentration and of the pH on the retention has been determined. The results show that variation of these parameters permits adjustment of the retention of these drugs over a wide range. The dynamic cation-exchange system developed was applied to the determination of halopemide and its main metabolite in plasma. The precision and detection limit of the method and the extraction efficiency were established. The time course of halopemide and plasma levels of patients chronically receiving halopemide are reported.