Fig. 2.

The effects of chronic buprenorphine on the priming strength of opioid full agonists. The ability of methadone (A), heroin (B), and oxycodone (C) to reinstate drug-seeking behavior before and during chronic buprenorphine treatment (0.1 and 0.32 mg/kg per day). Only one dose of oxycodone and methadone was tested during chronic treatment with 0.32 mg/kg per day. Left panels show the percentage injection lever responding, and right panels show the number of saline injections self-administered over a 30-minute session. Abscissae: dose (milligrams per kilogram) of opioid full agonist as intramuscular priming injection. Ordinate: percentage injection lever responding (left), number of saline injections (right).