Reinforcing and subjective effects of oral tripelennamine in normal human volunteers.

Tripelennamine is a prescription antihistamine with a history of abuse when combined parenterally with opioids. The present study examined the reinforcing and subjective effects of oral tripelennamine in a group of 18 normal, healthy adults. Self-administration behavior was measured with a discrete-trial choice procedure. Subjects first sampled color-coded capsules containing either placebo or tripelennamine (25 or 50mg). On three subsequent occasions, subjects were allowed to choose which color-coded capsule to self-administer. The number of times subjects chose tripelennamine over placebo was used as the primary index of reinforcing efficacy. Subjective effects questionnaires were used to measure mood before and several times after capsule ingestion. The low dose of tripelennamine produced no significant mood changes relative to placebo, and was chosen on 39% of occasions, not significantly different from chance. The high dose produced mild sedative-like effects, and was chosen on 33% of occasions, significantly less than expected by chance, indicating that this dose was aversive. The results demonstrate that oral therapeutic doses of tripelennamine are not reinforcing and do not produce positive mood changes in subjects without a history of drug abuse.