The convulsant effects of cocaine and its C2-epimer, pseudococaine on EEG, respiration, heart rate and behavior were studied in the rhesus monkeys with electrodes implanted in the brain. Intravenous injections of cocaine (3.0 to 8.0 mg/kg) and pseudococaine (3.0 to 7.0 mg/kg) in the animals produced a similar pattern of clonic convulsions accompanied by marked increases in the heart and respiratory rates with mydriasis and excessive salivation. However, both isomers showed different effects on the EEG and animal's behavior following convulsions; e.g., the cocaine-induced convulsions were followed by low-voltage fast waves in the EEGs associated with behavioral hyperexcitation, while pseudococaine-induced convulsions were followed by high-voltage slow waves associated with behavioral depression and drowsiness with intermittent sleep. Pseudococaine was more potent than cocaine in producing convulsions in the same monkeys. The durations of convulsions produced by these drugs were dose-dependent.

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Cocaine and pseudococaine: comparative effects on electrical after-discharge in the limbic system of cats.

The effects of cocaine and its dextroisomer pseudococaine on electrical after-discharge (AD) evoked by electrical stimulation of the hippocampus or amygdala were studied in cats with electrodes implanted in the brain. Intravenous injection of cocaine (2.0 to 4.0 mg/kg doses) produced a suppressive effect on the AD while producing low-voltage fast waves (LVFWs) in the electrical activities of the brain (EEG) associated with behavioral excitation. In contrast, pseudococaine at the same dose as cocaine failed to show a significant suppressive effect on the AD except at high doses (5.0 mg/kg). Pseudococaine produced high-voltage slow waves (HVSWs) in the EEG associated with behavioral depression. A linear dose-response relationship was observed for the suppressive effect of cocaine on the AD. The results suggested that the limbic system may be involved as a primary site of action of cocaine in the central nervous system (CNS).

Amygdala↗

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Disposition and metabolism of psi-cocaine (dextrococaine) in the rat.

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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.

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PubMedDate not supplied

Disposition of (15,16-3H)naltrexone in the central nervous system of the rat.

After injection of (15,16-3H)naltrexone (10 mg/kg s.c.) in male Wistar rats, peak concentrations of drug occurred in brain and plasma within 0.5 hr. Levels of naltrexone were sustained in brain between 2 and 24 hr and were barely detectable at 48 hr. Significant amounts of metabolities were present in brain and plasma at longer time periods. The t1/2 of naltrexone in brain and plasma were approximately 8.0 and 11.4 hr. respectively. The brain/plasma ratios of naltrexone at earlier times (0.5-1 hr) were higher than those at later times. The binding of naltrexone in vitro with rat plasma proteins in concentrations of 1-10 mug/ml ranged between 41 and 59% 6beta-Naltrexol was present in very small amounts in brain but not in plasma. In addition to 7,8-dihydro-14-hydroxynormophinone and 7,8-dihydro-14-hydroxynormophine, tentative evidence was obtained for three other metabolites of naltrexone in brain. These metabolites were also present in plasma in addition to free and conjugated naltrexone and its N-dealkylated metabolites.

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