Correlation of chlorpromazine levels in rat brain and serum with its hypothermic effect

The correlation between chlorpromazine (CPZ) levels in rat brain and serum with hypothermia was investigated. Even large differences between brain and serum concentrations of CPZ could be demonstrated at the two dosages of the drug investigated, the groups showed an identical hypothermic effect between 5 to 30 minutes, with maximum hypothermia being reached 1 hour. It also appears that when brain concentrations of CPZ were lower than 1 mug/g, body temperature returned to normal. We could not demonstrate any preferential uptake of CPZ into the hypothalamus, the proposed site at which CPZ acts to cause hypothermia.