effects of the opioid agonists morphine , l-methadone , ethylketazocine , u50,488 [ trans-3,4-dichloro-n-methyl-n- [ 2- ( 1-pyrrolidinyl ) cyclohexyl ] benzeneacetamide methanesulfonate hydrate ] , cyclazocine and bremazocine , and the nonopioid chlorpromazine were determined in pigeons responding under a fixed-ratio 30 schedule of food presentation before , during and after chronic morphine administration .
C0079314
ethylketazocine
C0010526
cyclazocine