Effects of Pioglitazone, a PPARgamma Receptor Agonist, on the Abuse Liability of Oxycodone

Inclusion Criteria: 1. Recreational use of prescription opioids at least once per month within the past year 2. No current major mood, psychotic, or anxiety disorder 3. Physically healthy 4. aspartate aminotransferase (AST) or alanine aminotransferase (ALT) within normal limits 5. Able to perform study procedures 6.21-45 years of age 7.Blood glucose concentration between 70-145 mg/dl for men and 70-125 mg/dl for women (fasting) 8.Hb \> 13 for men and Hb \> 11 for women with no other evidence of medical disorder resulting in blood loss or anemia/hematological disease Exclusion Criteria: 1. Physical dependence on any drugs, excluding nicotine and caffeine 2. Participants requesting treatment 3. Participants on parole or probation 4. Pregnancy or lactation: Female participants must agree to the use of a barrier control method of contraception (e.g. male and female condoms, diaphragms, cervical caps and contraceptive sponges used in combination with spermicide) 5. Current or recent history of significant violent behavior (within the past 6 months) 6. Current major Axis I psychopathology that might interfere with ability to participate in the study 7. Significant suicide risk 8. Current chronic pain 9. Current or history of congestive heart failure, edema, or diabetes mellitus 10. Sensitivity, allergy, or contraindication to opioids or pioglitazone 11. Unstable physical disorders that might make participation hazardous, such as end-stage AIDS, hypertension (blood pressure \> 140/90), or heart disease (please note that participants will be asked about previous visits to a cardiologist, chest pain, or strong palpitations; if these exist, they will be referred to a cardiologist and excluded unless cleared for participation by a cardiologist)