Coupling of microdialysis with capillary electrophoresis: a new approach to the study of drug transfer between two compartments of the body in freely moving rats.

The feasibility of in vivo microdialysis and capillary electrophoresis for pharmacokinetic studies was tested. Microdialysis probes were inserted in the jugular vein and brain of rats. After an intraperitoneal injection of phenobarbital, microdialysis was performed in the brain and the blood simultaneously in each rat under freely moving conditions. Capillary electrophoresis with ultraviolet absorption was used to measure phenobarbital in blood and brain dialysates. The time course of phenobarbital in the blood and in the extracellular space of the brain was followed. The results demonstrated that microdialysis can be used for pharmacokinetic studies in freely moving animals. Capillary electrophoresis has the potential to improve the time resolution of microdialysis. Other advantages of microdialysis and capillary electrophoresis for pharmacokinetic studies are discussed.