Fig. 1.

Effects of chronic buprenorphine treatment on oxycodone self-administration under choice conditions. (A) Percentage injection-lever responding during 90-minute session, before and during treatment with 0.32 mg/kg per day of chronic buprenorphine. (B) Total number of oxycodone injections self-administered. (C) Total drug intake (milligrams per kilogram) over 90 minutes. (D) Number of food reinforcers received as a function of oxycodone unit dose available for self-administration. Abscissae: unit dose of oxycodone available for self-administration. Ordinates: percentage injection lever responding (A); number of oxycodone injections (B); total drug intake, milligrams per kilogram (C); and number of food deliveries (D).