Reinforcing and discriminative stimulus properties of mixed agonist-antagonist opioids

A. M. Young, K. R. Stephens, D. W. Hein, J. H. Woods

Research output: Contribution to journalArticlepeer-review

87 Scopus citations


Nine mixed agonist-antagonist opioids were evaluated in macaque monkeys for their ability to serve as positive reinforcers and for their discriminative stimulus similarity to etorphine and ethylketazocine. For tests of reinforcing properties, various doses of each drug were substituted for codeine under a fixed-ratio 30 time-out 600 sec schedule of i.v. delivery. Discriminative properties were assessed in separate groups of monkeys for which etorphine and saline, or ethylketazocine and saline, were established as discriminative stimuli for responses maintained under a fixed-ratio 20 schedule of food delivery. Two patterns of reinforcing and discriminative stimulus properties were observed. Buprenorphine, butorphanol, GPA 1657, nalbuphine, propiram and WY 16225 (dezocine) functioned as positive reinforcers and occasioned etorphine-appropriate but not ethylketazocine-appropriate responses. dl-Profadol also functioned as a positive reinforcer; its stereoisomers occasioned etorphine-appropriate but not, in general, ethylketazocine-appropriate responses. In contrast, levallorphan and oxilorphan did not function as positive reinforcers and occasioned ethylketazocine-appropriate but no more than 30% etorphine-appropriate responses. Under these experimental conditions, the reinforcing and discriminative stimulus profiles of the mixed agonist-antagonist opioids paralleled those of etorphine-like (mu) or ethylketazocine-like (kappa) opioid agonists.

Original languageEnglish (US)
Pages (from-to)118-126
Number of pages9
JournalJournal of Pharmacology and Experimental Therapeutics
Issue number1
StatePublished - 1984
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Medicine
  • Pharmacology


Dive into the research topics of 'Reinforcing and discriminative stimulus properties of mixed agonist-antagonist opioids'. Together they form a unique fingerprint.

Cite this