Buprenorphine as Adjunct to Outpatient Induction Onto Vivitrol

Procedure 1: 5-day induction with increasing doses of oral naltrexone. Participants will receive XR-NTX on day five together with buprenorphine, and will continue receiving buprenorphine for 4 weeks until they receive 2nd XR-NTX dose. Procedure 2: 10-day induction with buprenorphine administered daily and increasing daily doses of oral naltrexone beginning on day 2 . On day 10 participants will receive XR-NTX dose, and another one 4 weeks later. No buprenorphine will be given beyond day 10. Procedure 3: 10-day induction with buprenorphine administered daily and increasing daily doses of oral naltrexone beginning on day 2 . On day 10 participants will receive XR-NTX dose, and another one 4 weeks later. Buprenorphine will continue for 4 weeks until the 2nd XR-NTX dose. All participants will receive weekly therapy with a study psychiatrist. All participants will receive open-label medication.