Abstract
This study was designed to document possible changes in caffeine kinetics in female rats both according to the stage of the oestrous cycle and in castrated animals. After a single 12 mg/kg ip dose during proestrus, oestrus, dioestrus, or 15 days after castration, the plasmatic clearance of caffeine varied significantly with higher values during oestrous. The other pharmacokinetic parameters did not vary significantly.