The purpose of this study is to evaluate the acceptability and safety of switching to Suboxone® (buprenorphine plus naloxone) and the effect of the switch on medication dispensing. Subjects, for whom a therapy with Suboxone® is indicated and planned prior to study enrollment and who are willing to participate, will initiate therapy on Day 1 of the study. The dosage will be adjusted between Day 2 to 7 depending on patient's needs and determined by the treating physicians in accordance with the SmPC of Suboxone®. Data will be collected at baseline, day 1 til 7, the end of weeks 2 and 4 and monthly up to the end of Month 12.