Effects of alprazolam on intravenous cocaine self-administration in rats.

The specificity of benzodiazepine pretreatment on the reinforcing efficacy of cocaine was investigated using a multiple schedule of cocaine and food presentation. Cocaine was available under a fixed-ratio 4 schedule of reinforcement during 1 h of the session, while food was delivered under a discrete-trial, fixed-ratio 10 schedule during the other. Following initial exposure to alprazolam, responding maintained by both cocaine and food was significantly reduced. However, tolerance quickly developed to the sedative effects of alprazolam on food-maintained responding, while no reduction in the effects of the drug on cocaine self-administration was observed. Alprazolam (0.5 to 4.0 mg/kg, IP) significantly reduced cocaine intake without affecting food-maintained responding following subsequent testing with the drug. These data suggest a potential specific effect (e.g., anxiolytic) of alprazolam in cocaine reinforcement.