Ketamine HCL Crystal, sold under the brand name Ketalar among others, is a medication mainly used for starting and maintaining anesthesia. It induces a trance-like state while providing pain relief, sedation, and memory loss. Other uses include for chronic pain and for sedation in intensive care. Heart function, breathing, and airway reflexes generally remain functional during its effects. Effects typically begin within five minutes when given by injection with the main effects lasting up to 25 minutes.
Common side-effects include psychological reactions as the medication wears off. These reactions may include agitation, confusion, or hallucinations. Elevated blood pressure and muscle tremors are relatively common, while low blood pressure and a decrease in breathing are less so. Spasms of the larynx may rarely occur. Ketamine has been classified as an NMDA receptor antagonist but its mechanisms are not well understood as of 2017.
Ketamine may be used for postoperative pain management. Low doses of Ketamine HCL Crystal may reduce morphine use, nausea, and vomiting after surgery.
It may also be used as an intravenous analgesic with opiates to manage otherwise intractable pain, particularly if this pain is neuropathic. It has the added benefit of counteracting spinal sensitization or wind-up phenomena experienced with chronic pain. At these doses, the psychotropic side-effects are less apparent and well managed with benzodiazepines. Ketamine is an analgesic that is most effective when used alongside a low-dose opioid; because, while it does have analgesic effects by itself, the doses required for adequate pain relief when it is used as the sole analgesic agent are considerably higher and far more likely to produce disorienting side effect. A review article in 2013 concluded, “despite limitations in the breadth and depth of data available, there is evidence that ketamine may be a viable option for treatment-refractory cancer pain”.
Low-dose ketamine is sometimes used in the treatment of complex regional pain syndrome (CRPS). A 2013 systematic review found only low-quality evidence to support the use of ketamine for CRPS.