Recommended Citation
Patel A, Gaiha R, Rao Shuai I, Knezevic N. Converting intravenous to oral ketamine in a cancer palliative patient. Presented at: Midwest Anesthesia Residents Conference (MARC); April 26, 2025; Indianapolis, IN.
Presentation Notes
Presented at: Midwest Anesthesia Residents Conference (MARC); April 26, 2025; Indianapolis, IN.
Abstract
Introduction: Ketamine is a dissociative anesthetic that was first developed in the 1960s as a safer pharmacological alternative to phencyclidine [1]. Its primary mechanism of action involves inhibiting the N-methyl-D-aspartate (NMDA) receptor which disrupts excitatory neurotransmission in the superficial dorsal horn [2]. This unique property not only provides sedation during anesthesia but also yields some analgesic and antidepressant effects. While ketamine is commonly administered intravenously, its use in the oral form remains limited due to its variable bioavailability and extensive first-pass metabolism. These challenges have hindered the widespread adoption of oral ketamine. As a result, there is a clear need to investigate the potential of oral ketamine as it can be particularly useful in situations where intravenous access is limited or when long-term administration of ketamine is needed. Case presentation: This case represents a 38-year-old female with PMHx of stage IV endometrial cancer with mets including pelvic wall s/p resection (10/23/2020), anemia, RLE DVT (while on AC) with right LE pain in the setting of chronic cancer pain and chronic opioid use who was admitted as a direct transfer for continuity of care and pain control. Her home regimen consisted of a MS Contin 30mg BID, Flexeril 5mg BID, Gabapentin 600mg TID, and oxycodone 10mg QID. Fentanyl patch (mcg/h) Dilaudid IV (mg) Dilaudid PO Total MME Ketamine Pain score Day 0 75 12.7 0 500 0 9-10 Day 1 75 4 0 330 15mg/h IV 7-9 Day 2 75 8 0 410 15mg/h IV 5-7 Day 3 75 18 0 610 40mg TID PO 7-9 Day 4 75 12 0 490 60mg TID PO 5-7 Day 5 100 0 24 450 60mg TID PO 3-5 On Day 0, the patient was initiated on a fentanyl patch and Dilaudid PCA, with a total Dilaudid usage of 6.7 mg through PCA and an additional 6 mg administered intravenously. The patient was still endorsing significant pain, so an IV ketamine infusion was started at a rate of 15 mg/h for two days. During this period, the patient’s Dilaudid requirement decreased on the first day, accompanied by an improvement in pain scores. On Day 3, the patient was transitioned to oral ketamine at 40 mg TID. However, this dose proved insufficient, as evidenced by an increased demand for Dilaudid. On Day 4, the oral ketamine dose was increased to 60 mg TID, which led to a progressive reduction in opioid requirements. By Day 6, the patient’s opioid use had decreased to 450 MME, with further improvements in pain scores. Conclusion: We were able to successfully achieve adequate pain control by incorporating intravenous (IV) ketamine into this patient’s analgesic regimen. The level of pain relief was maintained when transitioned from IV ketamine to oral ketamine, which was a critical step to facilitate her discharge. While our biggest challenge was determining the appropriate dose conversion from IV to PO, our case shows the feasibility of using PO ketamine for effective pain control in palliative cancer patients. 1. Hirota, K. et al. (2022) Neuropharmacology 216: 115-117 2. Mion, G. et al (2013) CNS Neurosci and Ther 19: 370-380
Type
Oral/Podium Presentation
Affiliations
Advocate Illinois Masonic Medical Center