Characterization of Oral Ketamine Use: A Retrospective Review

Ketamine is an N-methyl D-aspartate (NMDA) receptor antagonist used to treat pain at subanesthetic doses. Ketamine is beneficial for pain control in patients who have a high tolerance to opioids and are experiencing opioid-induced hyperalgesia. This study characterizes oral ketamine use for analgesia at a large academic hospital and reports safety outcomes for hospitalized patients. This study was a retrospective electronic health record (EHR) review of patients ≥ 18 years or older receiving oral ketamine. The primary endpoint was median ketamine starting dose and maximum dose (mg/kg/day) during treatment duration. Secondary outcomes included oral Morphine Milligram Equivalents (MMEs), buprenorphine dose, minimum and maximum pain scores on the first and last day of therapy. Safety endpoints were reported. The median starting dose was 1 mg/kg/day, and the median maximum dose was 1.6 mg/kg/day. Median MMEs decreased from the first day to the last day of oral ketamine therapy. The study population experienced a low incidence of safety events overall. Oral ketamine was administered safely for analgesia, with patients receiving ketamine doses that were on the lower end of the established therapeutic range. Evaluation of the efficacy and safety of oral ketamine use for analgesia should be further studied.