Ketamine and esketamine are efficacious for treatment-resistant depression. Unlike other antidepressants, ketamine lacks a therapeutic delay and decreases the risk for suicide. This cross-sectional study geographically characterized ketamine and esketamine prescribing to United States (US) Medicaid patients. Ketamine and esketamine prescription rates and spending per state were obtained. Between 2009 and 2020, ketamine prescribing rates peaked in 2013 followed by a general decline. For ketamine and esketamine in 2019, Montana (967/million enrollees) and Indiana (425) showed significantly higher prescription rates, respectively, relative to the national average. A total of 21 states prescribed neither ketamine nor esketamine in 2019. There was a 121.3% increase in esketamine prescriptions from 2019 to 2020. North Dakota (1,423) and North Carolina (1,094) were significantly elevated relative to the average state for esketamine in 2020. Ten states prescribed neither ketamine nor esketamine in 2020. Medicaid programs in 2020 spent 72.7-fold more for esketamine ($25.3 million) than on ketamine (0.3 million). Despite the effectiveness of ketamine and esketamine for treatment-resistant depression and anti-suicidal properties, their use among Medicaid patients was limited and highly variable in many areas of the US. Further research to better understand the origins of this state-level variation is needed.
Keywords: bipolar; depression; pharmacoepidemiology; pharmacotherapy; suicide.