COCAINE AND BENZOYLECGONINE IN SERUM MICROSAMPLES OF INTACT AND GONADECTOMIZED MALE AND FEMALE WISTAR RATS

Tail-tip plasma samples of intact and gonadectomized male and female W istar rats were analyzed for cocaine and benzoylecgonine. The samples were obtained from immobilized subjects 10 and 30 min following the Is t and 22nd intraperitoneal injections of 10 mg/kg cocaine hydrochlorid e. Gender differences in plasma cocaine or benzoylecgonine levels were not observed after the first injection of cocaine because many of the samples were below the detection limit. Cocaine plasma levels were mu ch higher after the 22nd injection, but gender differences were not ob served either 10 or 30 min following cocaine administration. Plasma le vels of benzoylecgonine were higher 30 min than 10 min after cocaine a dministration in intact and castrated male rats and ovariectomized fem ale rats but not in intact female rats. These data show that, in rats, gender differences in cocaine metabolism may be observed after repeat ed cocaine administration, but the exact mechanism remains to be eluci dated. (C) 1997 Elsevier Science Inc.