The hydrochloride salt of a synthetic derivative of cyclohexanone with analgesic and anesthetic activities. Although its mechanism of action is not well understood, ketamine appears to non-competitively block N-methyl-D-aspartate (NMDA) receptors and may interact with opiod mu receptors and sigma receptors, thereby reducing pain perception, inducing sedation, and producing dissociative anesthesia. Check for active clinical trialsusing this agent. or A drug used to cause a loss of feeling and awareness and to induce sleep in patients having surgery. It is also being studied in the treatment of nerve pain caused by chemotherapy. Ketamine hydrochloride blocks pathways to the brain that are involved in sensing pain. It is a type of general anesthetic. Also called Ketalar and ketamine.