The action of ketamine involves multiple mechanisms with multiple receptors. Ketamine is noncompetitive, reversible N-methyl-D-aspartate (NMDA) channel blocker which blocks the excited nerves, potentiates delta and mu opioid agonism and opioid potentiation, alters the nitric oxide guanosine monophosphate system, changes in cholinergic activity, and central dopamine and noradrenaline release. The NMDA channel blockade is especially unique to the mechanism of action of ketamine. This leads to quick onset of action (less than 5 minutes) and a short duration of activity when given in a single shot.
Indications of ketamine include anesthetic induction, maintenance, and perioperative pain management especially in patients with opioid tolerance, dependence or patients at risk of opioid related respiratory depression. Subanesthetic ketamine infusion are routinely used to treat complex regional pain syndrome and other causes of neuropathic pain. Ketamine has multiple systemic effects including central nervous system, cardiovascular system pulmonary system including the airways, and hepatic system. Side effects include nausea, headache, fatigue, dysphoria as well as dissociative experiences such as hallucination, delusion, or out of body experiences. These central nervous system side effects may be mitigated with use of benzodiazepine prior to ketamine use.