Ketamine is a drug
A drug, broadly speaking, is any substance that, when absorbed into the body of a living organism, alters normal bodily function. There is no single, precise definition, as there are different meanings in drug control law, government regulations, medicine, and colloquial usage.In pharmacology, a...

 used in human and veterinary medicine
Veterinary medicine
Veterinary Medicine is the branch of science that deals with the prevention, diagnosis and treatment of disease, disorder and injury in non-human animals...

. Its hydrochloride
In chemistry, hydrochlorides are salts resulting, or regarded as resulting, from the reaction of hydrochloric acid with an organic base . This is also known as muriate, derived from hydrochloric acid's other name: muriatic acid....

 salt is sold as Ketanest, Ketaset, and Ketalar. Pharmacologically
Pharmacology is the branch of medicine and biology concerned with the study of drug action. More specifically, it is the study of the interactions that occur between a living organism and chemicals that affect normal or abnormal biochemical function...

, ketamine is classified as an NMDA receptor antagonist
NMDA receptor antagonist
NMDA receptor antagonists are a class of anesthetics that work to antagonize, or inhibit the action of, the N-methyl d-aspartate receptor . They are used as anesthesia for animals and, less commonly, for humans; the state of anesthesia they induce is referred to as dissociative anesthesia...

. At high, fully anesthetic level doses, ketamine has also been found to bind to opioid
An opioid is a psychoactive chemical that works by binding to opioid receptors, which are found principally in the central and peripheral nervous system and the gastrointestinal tract...

 μ receptors
Mu Opioid receptor
The μ-opioid receptors are a class of opioid receptors with high affinity for enkephalins and beta-endorphin but low affinity for dynorphins. They are also referred to as μ opioid peptide receptors. The prototypical μ receptor agonist is the opium alkaloid morphine; μ refers to morphine...

 type 2 in cultured human neuroblastoma cells, however without agonist activity, and to sigma receptor
Sigma receptor
The sigma receptors σ1 and σ2 bind to ligands such as 4-PPBP, SA 4503, ditolylguanidine, dimethyltryptamine and siramesine.- Classification :...

s in rats. Also, ketamine interacts with muscarinic receptors, descending monoaminergic pain pathways and voltage-gated calcium channels.