Treatment of Severe Mucositis Pain With Oral Ketamine Mouthwash

Mucositis

Mucositis is an adverse effect as a result of chemotherapy and radiation treatments and has significant quality of life and clinical consequences. Mucositis is a result of direct cytotoxic damage as well as a cytokine-mediated inflammatory response and can affect the epithelial mucosal surfaces along the entire gastrointestinal tract. Mucositis manifesting in the oral cavity can be especially distressing to patients and may involve erythema, cracking, inflammation, bleeding and ulceration and typically begins 5-10 days after starting chemotherapy. Mucositis occurs in about 40% of patients receiving standard dose chemotherapy, 80% of patients receiving radiation therapy to the head and neck, and up to 100% of patients undergoing a bone marrow transplant.(1)

Pain from oral mucositis has been reported as the single most debilitating side effect by patients receiving bone marrow transplants. Mucositis is also the most common condition requiring analgesics during cancer therapy. Complications of pain from mucositis include inability to tolerate food or fluid intake, difficulty or inability to talk, excess mucus, gagging, sleep disturbances, and drooling. Mucositis may also require hospital admission or extended admission for total parenteral nutrition, intravenous analgesia, and/or intravenous antibiotics. Seventy percent of patients with a grade 3 or 4 mucositis will require a feeding tube. Mucositis also has the potential to impact the effectiveness of cancer treatment as it is a dose-limiting toxicity and results in cessation or reduction of treatment in 35% of patients (2,3,4)

Current standard of care focuses on palliation and includes systemic opiate analgesics for moderate to severe mucositis pain, topical anesthetics and mucosal coating agents such as lidocaine, benzocaine, dyclonine, diphenhydramine, doxepin, and benzydamine for moderate pain, and bland rinses for mild pain. Data supporting these management options are limited. Other agents that have been investigated with variable responses are oral capsaicin, oral sulfasalazine, and growth factor mouthwashes. (5)

Ketamine

Ketamine is a sedative hypnotic with anesthetic and analgesic properties. Ketamine works by selectively depressing the thalamoneocortical system, non-competitively blocking N-methyl-D-aspartate (NMDA) receptors, and having intrinsic sympathomimetic activity. Ketamine also appears to selectively interrupt association pathways in the brain producing somatesthetic sensory blockade. Ketamine is FDA-approved for induction and maintenance of general anesthesia but has also been used for procedural sedation, refractory severe pain, and acute respiratory failure in children. (6)

Topical administration of ketamine was shown to cause a reduction in allodynia in a double-blind placebo controlled study and peripheral administration of ketamine has antinociceptive efficacy similar to that of systemic administration which is likely mediated by NMDA antagonism (7). Ketamine may also potentiate the effects of other systemic opioid analgesics and may reverse opiate tolerance to some degree. Also, given that topical administration of opiates has a local effect, topical ketamine may produce a local tolerance reversal. Ketamine also has modest anti-inflammatory properties which could provide beneficial effects in mucositis pain relief. (8)

Ketamine oral rinse use was described in a case report of a 32 year old female with radiation-induced mucositis pain refractory to Clark's solution, transdermal fentanyl, and intravenous hydromorphone. Ketamine oral rinse was given as 20mg of drug in a 5ml artificial saliva solution every 3 hours as needed with continued PCA use. She experienced decreased pain at rest and with eating and was able to decrease the dose of her opiate analgesics. Her overall pain was reported as decreased from 9/10 to 3/10 with oral ketamine use. No adverse effects were reported other than one episode of swallowing the solution which resulted in transient sedative and psychomotor effects. (8)

A retrospective chart review of ketamine mouthwash use in 8 patients over a period of 4 years was conducted to determine safety and efficacy. Patients in this review received ketamine 20mg/5ml mouthwashes every 4 hours as needed. Seven of the 8 patients were post-hematopoietic stem cell transplant (post-HSCT) patients. Five patients had a documented improvement in mucositis pain and 4 patients experienced an adverse event. Adverse events consisted of mild confusion, nausea, vertigo, and hallucinations; however 2 of the 4 patients had reports of these symptoms prior to beginning ketamine mouthwashes but were still included in the analysis. Patients received an average of 17 doses over an average of 6 days. Reporting of pain scores were variable and difficult to quantify but the authors concluded that ketamine may provide a viable treatment option for mucositis pain. (9)

Rationale for study

Evidence for the use of an oral ketamine rinse suggests that it could provide a distinct benefit for patients suffering from pain and other clinical consequences of mucositis as a result of cancer treatments. No treatment is currently available that provides a profound relief from this pain and available evidence suggests that ketamine could be a useful tool in the arsenal of agents available to patients. Ketamine mouthwash was approved by the WVUH Pharmacy Nutrition and Therapeutics (PNT) Committee as a treatment option for mucositis pain. It is commercially available and currently used at our hospital. No prospective data exists objectively evaluating the potential benefits and possible adverse effects of ketamine oral rinse. We postulate that using ketamine as an oral mouthwash will provide pain relief for patients with significant distress due to pain from oral mucositis.