Ketamine got its start in Belgium in the 1960s as an anesthesia medicine for animals. The FDA approved it as an anesthetic for humans in 1970. At first its was used to treat injured soldiers on the battlefields in the Vietnam War and proved to be highly effective.
Emergency Responders began to carry Ketamine in their packs to be used as an anesthetic for medical emergencies. There was an instance that a Responder administered a dose to a calm a mentally agitated patient on the verge of a suicide attempt. That's how Rod Stewart, MD, says doctors began to realize that the drug had powerful effects against depression, anxiety, and other forms of mental illness, in both minor and acute cases.