The use of ketamine in cancer palliation

Cancer pain is caused by continuous tissue injury, which may be due to surgery, infiltration of the surrounding organs including nerves, as well as from mucositis after chemoor radiotherapy. Nerve involvement, chronic opioid therapy and continuous nociceptive input cause hyperalgesia. Chronic stimulation of the dorsal root neurons leads to hyperalgesia and resistance (tolerance) to μ opioid analgesics (hyperalgesia-tolerance). The NMDA receptor antagonist ketamine reverses tolerance to morphine. Ketamine aggravates the sedative effect of opioids and other drugs used for neuropathic pain, such as sodium valproate and amitriptyline. The pain experienced by cancer patients needs a multimodal approach, including ketamine. Although ketamine appears to be a useful analgesic, the literature dealing with ketamine as an analgesic lacks randomised controlled trials.