Participants were screened for up to 28 days prior to first investigational product (IP) administration. Eligible participants were admitted to the clinical unit on day -1 and were residential for a single period of 27 days/26 nights.~Participants were discharged from the clinical unit after completion of down-titration on the condition that all required assessments were performed and that there were no medical reasons for a longer stay in the clinical unit; which was the end-of-study visit (ESV). Prior to discharge, participants were provided with local buprenorphine and methadone providers for their reference.
The primary purpose of this study was to assess the safety and tolerability of multiple doses of buprenorphine/naloxone alone and buprenorphine/naloxone in combination with a single dose of ASP8062.~This study also assessed the potential for pharmacokinetic interaction between ASP8062 and buprenorphine/naloxone.