Influence of an alternative reinforcer on human cocaine self-administration

Identifying factors that modulate cocaine self-administration is fundamental to the development of effective strategies to treat and prevent cocaine abuse. In the present study, the influence of an alternative reinforcer on the probability of cocaine use was examined in four adult humans under controlled laboratory conditions. During eleven test sessions, subjects chose between cocaine hydrochloride vs. placebo or between cocaine vs. varying amounts of money (0-$2.00/choice). Subjects made a maximum of 10 exclusive choices per session. Cocaine and placebo were administered intranasally in 10 mg unit doses under double-blind conditions. Subjects exclusively chose cocaine over placebo demonstrating that the drug functioned as a reinforcer. During sessions comparing cocaine vs. money, choice of cocaine decreased as the amount of money available in the monetary option increased, with all subjects exclusively choosing the monetary option in the $2.00 per choice condition. These results systematically replicate and extend to humans prior findings in laboratory animals demonstrating that the availability of alternative, nondrug reinforcers can significantly decrease cocaine use.