Opioid Relapse & HIV Risk: 48 Versus 24 Weeks of Injectable Extended Release Naltrexone

1.2.1 Primary and Secondary Outcome Measures Primary outcomes are: 1\) Opiate positive urine tests; 2) HIV injecting risk. Secondary outcomes are: 1\) Time to relapse; 2) HIV sex risk; 3) Proportion of appointments kept; 6) Psychiatric symptoms; 7) Opioid craving; 8) Self-reported drug use; 9) Money spent for drugs; 10) Employment; 11) Arrests; 12) Overall adjustment; 12) Adverse events. Hypotheses are that: 1. Primary outcomes will significantly favor the 48-week Vivitrol condition; 2. Five or more secondary outcomes will favor the 48-week condition; none will favor the 24-week condition.