Ketamine in Chronic Pain: A Review

Summary & key facts

This review says that ketamine, given in doses lower than those used for anesthesia, can quickly reduce pain—especially nerve-related pain—and is well supported for use around surgeries where it also seems to lower the chance of long-term pain and the need for strong pain drugs after the operation. There is some hint it could help long-term pain and that its antidepressant effects might help people with chronic pain, but there are not many long-term studies yet. Ketamine can cause disturbing mental effects for some people, and doctors often give it with drugs like benzodiazepines to make it easier to use. More research is needed on long-term safety and who will benefit most.

Key facts:

• Ketamine at doses below anesthesia level can produce strong short-term pain relief, especially for pain that comes from nerve damage.
• When given around the time of surgery, ketamine has been linked to less chronic pain afterward and to lower use of opioid painkillers after the operation.
• There is only limited clinical evidence about ketamine's long-term benefits for chronic pain, so we do not yet know how well it works months or years later.
• Ketamine also has an antidepressant effect, which might help people who have both chronic pain and low mood.
• Some of ketamine's side effects affect thinking and perception (sometimes described as psychomimetic effects). These effects can make people stop treatment.
• Doctors often give ketamine together with benzodiazepines or with drugs that calm the nervous system (called alpha-2 agonists) to make treatment easier to manage.
• The review concludes that more research is needed to understand ketamine's long-term safety and to do a clearer risk-versus-benefit analysis for people with chronic pain.

Abstract

Ketamine has been used in the treatment of several pain syndromes, particularly those with a relevant neuropathic component. Sub-anesthetic doses of ketamine produce a potent analgesic effect, due to its inhibition of N-methyl-D-aspartate receptors and enhancement of descending inhibitory pathways. Its short-term analgesic effect is well-documented perioperatively, with an associated reduction in postoperative chronic pain and opioid consumption. Despite some evidence regarding its long-term benefits, the number of clinical studies is still limited. In addition to its analgesic effects, ketamine also possesses an anti-depressive action, which might be useful in the treatment of chronic pain patients. Several side effects have been described, the psychomimetic ones being the most relevant due to their impact on treatment adhesion. At present, co-administration of ketamine and benzodiazepines or α2-agonists facilitates its clinical application. Despite current evidence and increasing use, further investigation is still needed regarding its long-term safety profile and clearer risk-benefit analysis.

Topics

Anesthesia and Pain Management Pain Mechanisms and Treatments Treatment of Major Depression

Categories

Health Sciences Medicine Pharmacology

Tags

Analgesic Anesthesia Anesthetic Chronic pain Drug Intensive care medicine Internal medicine Ketamine Medicine Neuropathic pain Opioid Pharmacology Psychiatry Receptor

Substances

Ketamine

Conditions & symptoms

Chronic Pain Depression Chronic pain Sadness or low mood