Background and aimsExtended release buprenorphine injection (INJ-BUP) has been available in the United States since 2018. INJ-BUP has the potential to positively impact OUD treatment outcomes by providing additional treatment options and patient choice. We aimed to describe the availability and prescribing of INJ-BUP for Medicaid beneficiaries since its availability, nationwide and by state.MethodsTo assess availability, we measured the number of substance use disorder (SUD) facilities that offered INJ-BUP and accepted Medicaid insurance in 2018-2021 and calculated the percentage of all facilities offering medications of OUD. To assess prescribing, we measured the number of prescriptions for INJ-BUP paid by Medicaid 2018-2022 and calculated the percentage of all buprenorphine prescriptions paid by Medicaid. Data sources were publicly available.ResultsThe number of facilities that offered INJ-BUP and accepted Medicaid insurance increased from 360 (2.5% of all SUD facilities offering medication) in 2018 to 2,257 (13.3%) in 2021. The number of prescriptions for INJ-BUP paid by Medicaid increased from 4,322 (0.1% of all buprenorphine prescriptions) in 2018 to 186,861 (2.0%) in 2022. There was notable variability in the number of facilities and prescriptions by state.ConclusionsThere has been exponential increase in the number of INJ-BUP prescriptions but uptake is much less than observed in other countries in shorter time periods. Limited availability at SUD treatment facilities that accept Medicaid may be one barrier to access.