Assessing the Acceptability, Feasibility, Effectiveness and Cost-effectiveness of LADB

Inclusion Criteria: * Are 18 years old or older. * Are verified (by certified clinician) opioid dependents according to the International Classification of Diseases 11th Revision. * Are not pregnant (verified by screening). * Are eligible to receive OAMT at a participating site. * Consent to attend the clinic and adhere to clinical protocols * Have the capacity to consent to participating in research. * Provide written informed consent. Exclusion Criteria: * Have a history or presence of an allergic or adverse response (including rash or anaphylaxis) to BUP or the Atrigel® delivery system (a registered trademark of Tolmar Therapeutics Inc.) if Sublocade is chosen. * Have any contraindication to BUP or methadone. * Show signs of clinically significant medical conditions which would compromise compliance with the protocol and/or client safety in line with clinical guidelines for the administration of injectable BUP for OAMT. * Are currently taking oral or depot naltrexone therapy or are enrolled in any form of naltrexone therapy within 30 or 90 days prior to study screening, respectively. * Are in thepost partum period (defined as 6 weeks) or confirmed as pregnant. * Have an inability or unwillingness to provide informed consent or abide by the requirements of the study.