Interactions of cocaine with barbital, pentobarbital and ethanol.

This study deals with the interactions of cocaine with barbital, pentobarbital and ethanol in nontolerant and tolerant male Sprague-Dawley rats. Cocaine hydrochloride (50 mg) pellets implanted s.c. in rats prior to the i.p. injections of sodium barbital (150 mg/kg dose once daily for 4 days) potentiated the hypothermic response 2 hr after the barbital injection, when maximum hypothermia occurred. The s.c. implantation of the same type of pellets prior to the i.p. injections of sodium pentobarbital (75 mg/kg dose once daily for 5 days) potentiated the pentobarbital hypnosis as measured by the duration of loss of the righting reflex in animals. Cocaine pellets (12.5 mg) implanted s.c. in rats potentiated the hypnosis induced by ethanol (3.2 g/kg i.p.) and the implantation of the same type of pellets (12.5, 25 mg) in ethanol-tolerant rats restored the ethanol hypnosis to levels observed in acutely treated animals. The course of tolerance development to barbital-induced hypothermia or pentobarbital hypnosis did not appear to be affected by cocaine. The possible role of central monoamines in the potentiation of barbital hypothermia and pentobarbital and ethanol hypnosis by cocaine is discussed.