Discriminative stimulus properties of tripelennamine in the pigeon

Pigeons trained under a two-key drug discrimination procedure eventually learned to discriminate the antihistaminic tripelennamine (5 mg/kg) from saline. When 0.63–7.5 mg/kg doses of tripelennamine were administered in generalization test sessions, the percentage of responses directed to the tripelennamine-appropriate key varied directly with dose. At certain doses, the discriminative stimulus properties of the antihistaminics, diphenhydramine and pyrilamine, clearly generalized to tripelennamine, whereas intermediate generalization was evident with the antihistaminics, chlorpheniramine and promethazine. Chlorpromazine, cimetidine, d-amphetamine, diazepam, morphine, pentazocine, phenobarbital, and sodium valproate failed to produce tripelennamine-like patterns of responding.