Pioglitazone to Treat Opioid Withdrawal Symptoms

Background: * Opioid-withdrawal symptoms include runny nose, body aches, chills, sweating, and diarrhea. Many people have these symptoms when trying to stop using opioid drugs. Long-acting opioids like methadone and buprenorphine are used to help people stop using other opioids, but these drugs can cause the same withdrawal symptoms. There are no non-opioid drugs that are approved specifically to treat those symptoms. * Pioglitazone is a drug used to treat type 2 diabetes. In a research study, the drug allowed heroin users to decrease their methadone dose faster without much discomfort, and stay abstinent from heroin. Researchers want to learn more about how pioglitazone helps treat opioid withdrawal symptoms. Objectives: \- To test whether pioglitazone can reduce opioid withdrawal symptoms. Eligibility: \- Individuals between 18 and 65 years of age who will be using buprenorphine to treat opioid dependency. Design: * This study will last up to 17 weeks. Participants must come to the study clinic every day for at least 13 weeks. * Participants will be screened with a physical exam and medical history. They will also answer questions about drug use habits, and provide blood and urine samples. * Participants will take buprenorphine daily for 7 weeks. For the first 3 weeks, the dose will be increased to a level that should help stop the use of opioids. For the next 4 weeks, the dose will be decreased. Blood, urine, and breath samples will be collected at different study visits. Participants will also fill out questionnaires about mood, drug craving, and withdrawal symptoms. * After 1 week on buprenorphine, participants will start the study pill (pioglitazone or a placebo) every day. They will take the study pill for 13 weeks. * During the treatment period, participants will have drug counseling once a week for 30 minutes. * Some participants have other tests as part of this study. These tests include functional magnetic resonance imaging scans to look for change