Scientific goals. The primary goal is to determine if simultaneous abstinence from heroin and cocaine can be elicited by combining two approaches: flexible methadone dosing and voucher-based CM. Secondary goals include: 1) comparing saliva and plasma levels of methadone, cortisol, and prolactin as predictors of treatment outcome; and 2) evaluating the impact of methadone maintenance on renal function, lipid profile, and cardiac function.
Methods. During an initial 6-week baseline phase, cocaine-abusing opioid-dependent outpatient participants (300 enrolled; 180 evaluable) will be stabilized on methadone 70 mg/day. At the end of baseline, participants who continue to use heroin and cocaine will be randomized to one of two dosing regimens and one of two CM conditions. In the flexible-dose regimen, participants will receive individualized dose increases (15 mg/day) to a maximum of 190 mg /day, based on heroin use and withdrawal. In the fixed-dose regimen, participants methadone dose will be increased to 100 mg/day and remain fixed there. Dose-group assignment will be double-blind: investigators will determine participants individualized dose increases, but only the pharmacists will know which participants actually receive them. The two CM conditions will be: vouchers contingent on cocaine-negative urine specimens, or noncontingent vouchers (i.e., vouchers independent of urine cocaine screen results). The main outcome measure will be the percentage of urines simultaneously negative for both cocaine and illicit opiates during treatment. For the concurrently run pharmacokinetic-pharmacodynamic portion, saliva and blood samples will be taken at regular intervals to determine levels of methadone, cortisol, and prolactin as predictors of treatment outcome. For the concurrently run medical-outcomes portion, urine (renal function), blood (lipid profile), and ECGs (cardiac function),will be obtained at set intervals.
Hypothesis. Flexible methadone dosing and voucher-based CM will be safe and result in greater simultaneous abstinence from heroin and cocaine, higher treatment retention, and higher health-related QOL when compared to fixed methadone dosing and the absence of CM.
Benefits. Participants will receive methadone, counseling, and some medical care at no charge. The methadone and voucher interventions are likely to reduce participants' use of heroin and cocaine. Counseling will include management of HIV risk behaviors. The study incorporates participant safety monitoring and will provide information relevant to improving the health and safety of community methadone-maintenance patients. The pharmacokinetic-pharmacodynamic part of the study does not benefit participants directly, but may lead to the development of more useful and less invasive drug-monitoring methods.
Risks. Participants may experience side effects from methadone, discomfort during methadone withdrawal, and discomfort (or, rarely syncope) from blood draws.
