| Sumario: | BACKGROUND: Ropinirole, a D(2)/D(3)/5-HT(1A) agonist, is used for the treatment of Parkinson's disease and restless leg syndrome, and is currently being evaluated as a treatment for cocaine dependence. However, there is little information available on ropinirole's reinforcing effects. METHODS: The current study tested ropinirole in monkeys (n=7) trained to self administer cocaine on a fixed-ratio 25 (FR 25) schedule of reinforcement to determine if it would function as a reinforcer. In addition, a behavioral economics approach was used in four monkeys to compare the reinforcing effectiveness of ropinirole to cocaine. RESULTS: Cocaine (0.01-0.3mg/kg/injection) functioned as a reinforcer in all monkeys under the FR 25 schedule, and ropinirole (0.01-0.1mg/kg/injection) functioned as a reinforcer in all but one. Furthermore, cocaine was a more effective reinforcer than ropinirole as indexed by demand functions. CONCLUSION: The current data indicate that ropinirole has reinforcing effects in monkeys, although its effectiveness as a reinforcer is relatively weak.
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