For over 30 years, methadone has been used to treat opioid addiction. Since methadone is effective in reducing withdrawal symptoms, it is used as a method of detoxification for opiate addicts. However, methadone is not effective in treating other drugs of abuse, such as cocaine. Tiagabine is a drug that enhances levels of gamma aminobutyric acid (GABA), a chemical found in the brain and spinal cord. The objective of this study is to determine the effectiveness of tiagabine in modifying cocaine-using behavior and reducing opiate withdrawal symptoms among newly admitted methadone-treated patients.~This 16-week, double-blind, placebo-controlled clinical trial will involve 120 participants who are both cocaine- and opioid- dependent. Participants will be randomly assigned to receive either tiagabine or placebo, while concurrently receiving methadone treatment. Baseline cocaine use will be determined during the first two weeks of treatment. The study will include three overlapping phases. The first phase will include a one-week fixed methadone induction (Week 1), as well as flexible methadone stabilization (Weeks 2-13). Phase two will consist of a 12-week treatment period (Weeks 2-13). This will consist of tiagabine induction and stabilization. Phase three will include a 4-week taper, detoxification, or transfer period (Weeks 14-17). After completion of treatment, a 3-month follow-up visit will occur.
Many opioid-dependent individuals are also dependent on cocaine. Methadone is a widely used and effective method for treating opioid dependence. However, it is not effective in treating other drugs of abuse. The purpose of this study is to determine the effectiveness of another drug, tiagabine, for treating cocaine dependence in opioid-dependent individuals already receiving methadone treatment.