Employment-based reinforcement of adherence to oral naltrexone in unemployed injection drug users: 12-month outcomes

Abstract

Oral naltrexone could be a promising relapse-prevention pharmacotherapy for recently detoxified opioid-dependent patients; however, interventions are often needed to promote adherence with this treatment approach. We recently conducted a study to evaluate a 26-week employment-based reinforcement intervention of oral naltrexone in unemployed injection drug users (Dunn et al., 2013). Participants were randomly assigned into a contingency (n = 35) group required to ingest naltrexone under staff observation to gain entry into a therapeutic workplace or a prescription (n = 32) group given a take-home supply of oral naltrexone and access to the workplace without observed ingestion. Monthly urine samples were collected and analyzed for evidence for naltrexone adherence, opioid use, and cocaine use. As previously reported, contingency participants provided significantly more naltrexone-positive urine samples than prescription participants during the 26-week intervention period. The goal of this current study is to report the 12-month outcomes, which occurred 6 months after the intervention ended. Results at the 12-month visit showed no between-groups differences in naltrexone-positive, opioid-negative, or cocaine-negative urine samples and no participant self-reported using naltrexone at the follow-up visit. These results show that even after a period of successfully reinforced oral naltrexone adherence, longer-term naltrexone use is unlikely to be maintained after reinforcement contingencies are discontinued. (PsycINFO Database Record

Trial registration: ClinicalTrials.gov NCT00149669.

Figure 1. Urinalysis Test Results

Urinalysis-testing results. The X-axis is study visits. Visits include results from the end of the induction period, immediately prior to randomization (R), results from 6 monthly assessments during the 26-week intervention, and results from the 12-month outcomes after the intervention ended. The data on the Y-axis are percent naltrexone-positive samples (top panel), representing naltrexone-adherence; and percent opioid-(middle panel) and cocaine-(bottom panel) negative samples, representing opioid and cocaine abstinence. Contingency participants are designated by filled symbols, and Prescription participants are designated by open symbols. Missing samples have been treated as negative for naltrexone, and positive for opioids and cocaine. Data is adapted from Dunn et al., 2013 with permission.