The ability of pioglitazone (PIO) to alter the effects of opioids in humans has not been characterized in a controlled laboratory setting. Accordingly, the proposed investigation seeks to examine the effects of PIO on oxycodone, one of the most commonly used and abused opioid drugs in the U.S. (Davis et al., 2003). More specifically, the primary aim of this investigation is to characterize the subjective effects of oxycodone under maintenance on various doses of PIO (0, 15, and 45 mg) in non-dependent, prescription opioid abusers. Secondary aims of the study are to examine the influence of PIO on the analgesic, cognitive, and physiological effects of oxycodone.

This 9-week investigation will use an inpatient/outpatient design in which participants will be maintained on ascending doses of pioglitazone (3 weeks on placebo followed by 3 weeks on PIO 15 mg followed by 3 weeks on PIO 45 mg). At the end of each maintenance period the effects of oxycodone (0, 10, and 20 mg) will be examined during a single laboratory session using a cumulative dosing procedure.

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)

Data has been presented at conferences and being prepared for a peer-review publication.

Recreational prescription opioid users.

Adverse events were assessed daily throughout the study.

A study nurse queried participants concerning any adverse events using the Systematic Assessment for Treatment Emergent Events (SAFTEE)