These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: A primate model of polydrug abuse: cocaine and heroin combinations.
    Author: Mello NK, Negus SS, Lukas SE, Mendelson JH, Sholar JW, Drieze J.
    Journal: J Pharmacol Exp Ther; 1995 Sep; 274(3):1325-37. PubMed ID: 7562505.
    Abstract:
    Abuse of cocaine-opiate combinations ("speedballs") reported clinically was simulated in a rhesus monkey model of simultaneous cocaine and heroin self-administration. The reinforcing effects of nine cocaine-heroin combinations (cocaine [0.001, 0.01 and 0.10 mg/kg per injection i.v.] and heroin [0.0001, 0.001 and 0.01 mg/kg per injection i.v.]) were evaluated for 10 days on a second-order fixed ratio of 4 (variable ratio of 16:S) schedule and compared with self-administration of cocaine and heroin alone. Dose-effect curves for cocaine-heroin combinations usually were similar to those for cocaine and heroin alone, and intermediate doses maintained equivalent high levels of drug self-administration. No toxic effects were observed. In drug discrimination studies, cocaine (0.004-1.3 mg/kg) substitution resulted in a dose-dependent generalization to the training dose (0.4 mg/kg i.m.) in all five monkeys. Heroin substitution (0.01-1.0 mg/kg i.m.) resulted in dose-dependent and complete generalization to cocaine in three of five monkeys. Heroin pretreatment (0.1-0.18 mg/kg i.m.) did not change the cocaine discrimination dose-effect curve. Pretreatment with an opiate antagonist, quadazocine (0.1 mg/kg i.m.), had no effect on the discriminative stimulus effects of cocaine but antagonized the cocaine-like discriminative stimulus effects of heroin. Pretreatment with a dopamine antagonist, flupenthixol (0.018 mg/kg), antagonized the discriminative stimulus effects of cocaine but did not affect the cocaine-like effects of heroin. These findings demonstrate the feasibility of maintaining self-administration of cocaine-heroin combinations and suggest that cocaine and heroin have similar reinforcing and discriminative stimulus effects in rhesus monkeys.
    [Abstract] [Full Text] [Related] [New Search]