Pharmacogenomic Testing to Optimize Opioid Use Disorder Treatment: Acceptability and Feasibility Trial - ABSTRACT Research on Pharmacogenomics (PGx) and opioid use disorder treatment is rapidly expanding and supports the likely high impact of using PGx in opioid use disorder treatment, however most published studies have not researched the clinical application of PGx. To address this critical gap and exert a high, sustained impact on the field of personalized medicine in substance use disorder treatment, this study will assess the acceptability and feasibility of PGx guided opioid use disorder treatment; promoting the National Institute on Drug Abuse mission by advancing science on addiction treatment and applying that knowledge to improve individual and public health through advances in personalized medicine for people with substance use disorder. This study will: 1) Identify barriers and facilitators impacting the acceptability and feasibility of a PGx testing protocol to inform opioid use disorder treatment by engaging patients, providers, clinic staff, and administrators in OUD treatment in open and closed ended surveys to identify barriers and facilitators; 2) Develop and evaluate evidence based educational resources for providers of medications for opioid use disorder and their patients by creating and evaluating digital education materials based on Aim 1 results and current literature; and 3) Evaluate the acceptability and feasibility of PGx guided methadone dosing through an 8-week randomized controlled trial (arms: PGx, services-as-usual) where primary outcomes of acceptability and feasibility are assessed. Secondary outcomes will include patient engagement, treatment adherence, substance use, cravings, and withdrawal symptoms. Post-intervention, methadone providers who had patients in the study will be surveyed on feasibility, acceptability, appropriateness, change in prescribing, comfort using PGx, and suggestions for improvement. Medication dosing based on PGx holds the potential to decrease deaths, increase treatment retention, and reduce the use of non-prescribed opioids through personalized medicine, this study will take the first steps toward examining that potential. Situated in a richly supportive environment in the internationally regarded Program of Excellence in Addictions Research, I have access to many well established and funded mentors, space, equipment, software, finances, and protected time to conduct my research. The proposed training plan integrates mentorship from experts in clinical trials (McPherson), pharmacogenomics (Scott) clinical application of PGx (Limdi), biomedical ethics related to genetics (May), and opioid use disorder treatment (Layton); and training in Ethical, Legal and Social Implications central to patient and provider trust and uptake of genomics in substance use disorder treatment, clinical application of PGx to substance use disorder treatment, and guidance in developing my research career and laboratory. This Mentored Research Scientist Development Award will build on my previous training, allowing me to pursue my long-term career goal of becoming an independent investigator with an established program of research poised for high scientific impact and focused on the intersection of Personalized Medicine and Substance Use, through PGx testing.