Jack Williams Shteamer, Mayson Augustus Callaway, Parth Patel & Vinita Singh

Ketamine is a potent NMDA antagonist which is frequently used in the treatment of acute and chronic pain, sedation, induction and maintenance of anesthesia, and ICU sedation. It exerts its NMDA antagonism by binding to the phencyclidine receptor site when the channel is open. With ketamine’s ability to inhibit these receptors, it is postulated that ketamine can help treat chronic neuropathic pain. Additionally, ketamine has been shown to be a rapid acting antidepressant, making it useful in the concomitant treatment of pain and depression. While the elimination half-life of ketamine is 5.9 h, after intravenous (iv.) bolus administration, its analgesic effects have been reported to last up to 12 weeks,. The drug is metabolized by hepatic CYP3A4 to mostly norketamine, which may contribute to its analgesic properties. It is commercially available as a racemic mixture in USA; however, the S-enantiomer (now available in USA in intranasal formulation for depression) is four-times more potent than the R-enantiomer (and two-times more potent than the combination) . Due to its lipid and water solubility, ketamine can be administered intravenously, by intramuscular and subcutaneous injection, transdermally, transmucosally and orally, although it has substantial first-pass metabolism and its oral bioavailability is 17–29%.