Brain pharmacokinetics of centrally acting drugs, a quantitative autoradiographic study.

The concentration kinetics of 14C labeled diazepam, chlorpromazine and iodoantipyrine were studied in several regions of rat brain shortly after intravenous (i.v.) administration by a quantitative autoradiographic method. A highly significant linear relationship was found between regional diazepam resp. chlorpromazine concentration, and regional cerebral blood flow (rCBF) 1 min after injection. Moreover, a linear relationship was found between rCBF and, on the other hand, firstly diazepam concentration decrease between 1 and 2 min, secondly increase in chlorpromazine concentration between 1 and 5 min, and finally decrease of chlorpromazine concentration between 5 and 30 min. The regional kinetics of diazepam were compared with those of iodoantipyrine, a tracer assumed to be freely diffusible through the blood-brain barrier.