• Lisa S Middleton, Michelle R Lofwall, Paul A Nuzzo, Anthony J Siegel, and Sharon L Walsh.
• Department of Behavioral Science, University of Kentucky, Lexington, KY 40502, USA. sharon.walsh@uky.edu
• Exp Clin Psychopharmacol. 2012 Aug 1;20(4):310-7.

AbstractOxycodone, an opioid with known abuse liability, is misused by the intranasal route. Our objective was to develop a model of intranasal oxycodone self-administration useful for assessing the relative reinforcing effects of opioids and potential pharmacotherapies for opioid use disorders. Healthy, sporadic intranasal opioid abusers (n = 8; 7 M, 1 F) completed this inpatient 2.5-week, randomized, double-blind, placebo-controlled, crossover study. Each intranasal oxycodone dose (0, 14 & 28 mg) was tested in a separate 3-day block of sessions. The first day of each block was a sample session in which the test dose was given. Two randomized progressive ratio sessions were conducted on the next 2 days: (1) subjects could work for the test dose over 7 trials (1/7th of total dose/trial), and (2) subjects could work for either a portion of the dose (1/7th) or money ($3) over 7 trials. Physiological and subjective measures were collected before and after drug administration for all sessions. Subjects never worked to self-administer placebo regardless of whether money was available. In both self-administration sessions, oxycodone self-administration was dose-dependent. Subjects worked less for drug (28 mg oxycodone) when money was available but only modestly so. Oxycodone dose-dependently increased VAS ratings of positive drug effects (e.g., "like") during sample sessions (p < .05). These reports were positively correlated with self-administration behavior (e.g., "like," r = .65). These data suggest that both procedures are sensitive for detecting the reinforcing properties of intranasal oxycodone and may be used to further explore the characteristics of opioid compounds and potential pharmacotherapies for treatment.

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