Stress is one of the more common reasons cited by addicts for continual drug use and relapse. Treatment approaches that target both drug-induced and stress-induced relapse may prove to be more beneficial than targeting drug-induced relapse alone. Lofexidine is a drug that reduces the physical symptoms of opiate withdrawal and may prove to have stress-reducing capabilites in drug addicts. The purpose of this study is to determine the maximal safe dose of lofexidine tolerated in naltrexone-treated heroin addicts and to find an optimal lofexidine induction schedule.

Stress is one of the more common reasons cited by addicts for continual drug use and relapse. Naltrexone treatment of opiate addicts suffers from high rates of drop-out and relapse. This may be a result of naltrexone's inability to reduce symptoms of stress during early recovery. Treatment approaches that target both drug-induced and stress-induced relapse may prove to be more beneficial than targeting drug-induced relapse alone. Lofexidine is a drug that reduces the physical symptoms of opiate withdrawal and may prove to have stress-reducing capabilities. The purpose of this study is to determine the maximal safe dose of lofexidine tolerated in naltrexone-treated opiate addicts and to find an optimal lofexidine induction schedule. The study will also assess any side effects that occur during a discontinuation phase of lofexidine.

This pilot study will last a total of 8 weeks. Recently detoxified opiate dependent participants who are eligible for naltrexone treatment will enter a 4-week single-blind dose tolerability phase, during which participants will receive naltrexone and 1 of 3 twice-daily lofexidine induction schedules. All participants will be required to remain in the clinic for 2 hours immediately following dosing in order to monitor vital signs and side effects. Study visits will occur three times each week, at which time naltrexone medication for self-administration will be handed out and participants will be evaluated in terms of tolerability to treatment. After the 4 weeks of treatment, a double-blind lofexidine detoxification phase using a 5-day taper will occur. Participants will be randomly assigned to one of two maintenance-taper schedules. The first group will undergo a 5-day tapering, followed by a placebo for three weeks, followed by a 5-day tapering during Week 4. Withdrawal symptoms and side effects will be evaluated.

Inclusion Criteria:

• Meets DSM-IV criteria for opiate dependence
• Use of heroin at least 3 times per week during the 3 months prior to entering opiate detoxification
• Documented positive urine toxicology test for opiates
• Successful initiation on naltrexone treatment as indicated by stabilization on 50 mg of naltrexone once a day
• Reads English

Exclusion Criteria:

• Regular use of anticonvulsants, sedatives/hypnotics, prescription analgesics, antihypertensives (including clonidine), antirythmics, antiretroviral medications, and tricyclic antidepressants
• Psychotic or otherwise severely psychiatrically disabled (e.g., suidical, homicidal, currently manic)
• Abstinent from opiates for more than four weeks prior to naltrexone initiation
• Any medical problems that might make naltrexone treatment unsafe, such as hepato-cellular injury as evidenced by abnormal liver enzyme tests (including SGOT, SGPT, and GGT levels greater than three times normal) and a history of cirrhosis
• Hypotension with a resting blood pressure below 90/50 mm Hg
• Pregnant, breastfeeding, or refusal to use a reliable form of contraception throughout the study