Clonidine for Relapse Prevention in Buprenorphine-Maintenance Patients

Background: * Though the drug buprenorphine effectively treats dependence on opioids like heroin, some abstinent patients relapse to use during treatment. This relapse may be triggered by stress or stressful situations, and buprenorphine probably has no specific protective effect in these situations. Buprenorphine probably also has no specific effect on relapse to cocaine use. * Research has shown that clonidine, a drug originally prescribed to treat high blood pressure and some symptoms of opioid withdrawal, can help block stress-induced relapse to heroin and cocaine seeking in rats. Researchers are interested in studying whether a combination of clonidine and buprenorphine may be more effective in preventing drug relapse than administering one of the medications alone. Objectives: \- To determine whether clonidine, given to abstinent patients maintained on buprenorphine, is more effective than placebo in preventing relapse to heroin or cocaine use. Eligibility: \- Individuals between 18 and 50 years of age who are current cocaine or heroin users seeking treatment. Design: * The study will last up to 36 weeks, with four phases of treatment and a follow-up evaluation. Three times a week, participants will be asked to report illicit drug use and provide urine and breath samples. Throughout the study, participants will receive individual counseling in weekly 40 60 minute sessions. Other samples and tests will be scheduled as required by the study researchers. * Patients will be stabilized on daily buprenorphine over the first 14 days of the study. * Weeks 1 8: Participants will receive vouchers for regular substance-free urine samples. Those who successfully complete this phase will continue to the next part of the study. * Weeks 7 9: Participants will receive either clonidine or placebo along with the buprenorphine. The dose of clonidine will be stabilized during this time. * Weeks 9 22: Participants will continue to receive either clonidine or placebo along w