mr peabody
Bluelight Crew

Ketamine in pain management*
Lee Chang , Suman Rajagopalan, Sanjay Mathew, Carlos Zarate Jr.
As the use of ketamine as an anesthetic agent grew among practitioners, it was soon discovered that ketamine had additional properties that could benefit patients. As it was known that phencyclidine had analgesic properties, it was therefore hypothesized that ketamine would also have such effects. Research was started by healthcare providers in varying specialties to examine the use of ketamine as a potential treatment for pain management. Although the different pharmaceutical governing bodies have currently not approved the use of ketamine for pain management, the drug is used by practitioners to treat various pain conditions, including cancer pain, chronic pain, and perioperative pain.
Cancer pain management
Currently, ketamine is used in subanesthetic doses along with opioids to treat cancer pain, especially when opioids alone are ineffective in alleviating pain. Ketamine can be administered orally, intravenously, or subcutaneously for the relief of pain. A Cochrane review evaluating the use of ketamine in the management of cancer pain identified seven randomized control trials (RCTs) and 32 case reports or case series Only two RCTs were included in their analyses that showed an improvement in cancer-related pain when used along with morphine. Of the 32 case reports that were included in the same review, most showed an improvement in pain control when ketamine was used along with morphine. The authors concluded that more RCTs are required to assess the benefits and risks involved with the use of ketamine as an adjuvant to opioids for cancer pain.
Chronic pain therapy
Ketamine has been successfully used to treat different forms of chronic pain, including the treatment of chronic neuropathic pain, phantom and ischemic limb pain, postherpetic neuralgia, orofacial pain including trigeminal neuralgia, fibromyalgia, and chronic regional pain syndromes. Patients with complex regional pain syndromes who were administered low-dose ketamine infusions exhibited an improvement in pain scores for weeks following the treatment. Following administration of ketamine through an epidural catheter, one case study describes pain relief in a patient suffering from complex regional pain syndrome that was refractory to other treatments. In patients with fibromyalgia, ketamine increased tolerance to pain, decreased pain at tender points, and reduced muscle pain and referred pain. Current data suggest that instead of acting as a traditional analgesic, ketamine may more effectively reduce symptoms of allodynia and hyperalgesia. Younger patients and those with a short duration of pain seem to be more likely to have a positive response to treatment with ketamine. Oral dosing for ketamine has varied widely from 30 to 1000 mg/day, suggesting a wide therapeutic window. While there is sufficient evidence to demonstrate its benefit with short-term use, more studies are needed to establish the long-term effects of ketamine and the dose required for effective treat-ment with minimal side effects.
Acute perioperative pain
The analgesic effects of ketamine are believed to be, at least in part, due to its effects on central sensitization and neuronal modulation of pain. Low doses of ketamine may have either synergistic or additive analgesic effects when used in combination with opioids for postoperative pain. Ketamine is an effective adjuvant, particularly for upper abdominal, thoracic, and major orthopedic surgeries. The analgesic effect of ketamine does not depend on the type of opioid administered, the dose of ketamine, or the timing of ketamine administration. Administration of ketamine prior to the surgical procedure to determine if there was a decrease in postoperative pain scores or the amount of opioids required has been studied with variable results. Ketamine in small doses has also been added to patient-controlled analgesia (PCA) with morphine following thoracic surgery. This combination of morphine-ketamine PCA was found to provide superior analgesia and decrease the requirement of morphine with no increase in the incidence of hallucinations or psychological side effects.
*From the study here: https://www.academia.edu/30709950/Ketamine_for_Treatment-Resistant_Depression
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