Low-dose ketamine as an adjuvant for pain control in a cancer patient: a case report

This case report outlines the efficacy of repeated low-dose ketamine infusions (<35mg/70kg) as an adjuvant pain control medication for a terminally-ill cancer patient. The patient reported a sustained reduction in pain level and a reduction of total opioid usage in response to three consecutive ketamine infusions, which implicates its utility for improving the treatment of refractory pain within palliative care.

Abstract

“Introduction: Cancer patients often suffer from pain related problems such as under-treatment of pain, ineffective and persistent opioid administration as well as adverse opioid use outcomes. There is a growing need for non-opioid analgesic alternatives for patients undergoing treatment for obstinate pain. Ketamine is a fast-acting N-methyl-D-aspartate (NMDA) receptor antagonist that has been emerging as an effective medication for pain alleviation. While protocols have been established for the use of Low-Dose Ketamine (LDK) for post-operative pain, there is growing evidence for using LDK as a clinical alternative to opioids in a palliative care setting.

Methods: This case study involves monitoring the efficacy of LDK treatment in combination with opioid analgesics in a cancer patient in a hospital setting. This is a very selected case of a patient with Metastatic Prostate Cancer (Gleason 9 Adenocarcinoma) where LDK was shown to be efficacious at reducing pain when opioids and standard pain medications were not satisfactory.

Results: While the study involved using a relatively novel pharmacological protocol and close patient monitoring, the patient reported a sustained reduction in pain level based on the Numerical Rating Scale for months after the termination of LDK infusions. Moreover, the treatment also resulted in a reduction of total opioid usage after the addition of LDK.

Discussion: Although additional research is needed to ascertain optimal dosing schedules and route of Ketamine, given these promising findings, Ketamine may be a useful option for improving the treatment of refractory pain in patients with cancer and a good tool in palliative medicine for treating neoplastic pain.”

Authors: Sapan Patel, Vivas Tatachar, Aditya Bikram Singh, Julia Galea, Emma Fattakhov & Gurjinder Kaur

Summary

Introduction

Pain is the most common symptom for patients diagnosed with cancer, and opioids remain to be the mainstay of pain treatment. Low-dose ketamine (LDK) infusion can be used to better manage pain and reduce complications from high-dose opioid use.

Case presentation

A 55-year-old male was referred to palliative care with secondary unmanageable lower back pain and local hip pain due to bone metastasis from metastatic prostate cancer. He was prescribed a myriad of medications including Atorvastatin, Bisacodyl, Gabapentin, Metoprolol, and several opioid painkillers.

The patient was receiving 458.8 morphine milligram equivalents (MME) per day, but was still reporting an average pain of 9/10 on the Numerical Rating Scale. The patient was considered for the LDK infusion, and potential benefits were clearly observed.

A local LDK infusion protocol was established in 2019 under federal and institutional guidelines. The protocol allowed the use of intravenous LDK titration (0.5 mg/kg) as an adjunct to opioid treatment.

Observational data was collected regarding pain characteristics, pain score assessment, vitals, respiratory depression, tolerance and overall satisfaction. The NRS was routinely monitored every 4 hours. A patient undergoing Palliative Care treatment experienced a daily alleviation of pain to the level of 5 on the NRS, alongside a 32.43% reduction in opioid usage. The patient reported feeling less total pain following LDK administration, and a complete termination of Fentanyl use.

Overall, LDK infusions in a Palliative Care setting were effective in alleviating symptoms of pain and reducing opioid use.

All procedures were performed in accordance with the ethical standards of the institutional and/or national research committee(s) and the Helsinki Declaration.

Discussion

Acute pain is a significant issue in the treatment of cancer. It is difficult to assess the level of pain experienced by cancer patients due to concerns of addiction, reluctancy to complain, and side effects of medications.

Patients with cancer-related pain are frequently resorted to opioid use for pain management. However, under-treatment persists and does have significant negative impacts on the quality of life of patients.

A patient with metastatic prostate cancer was given low-dose ketamine (LDK) infusions for a 5-day period, and was noted to be in “great spirits” after receiving the LDK infusions. Ketamine has been shown to have anti-depressive actions in addition to its ability to relieve pain.

Ketamine is an NMDA receptor antagonist that prolongs the effect of opioid stimulation by improving the sensitization of opioid receptors. It has been shown to reduce pain in cancer patients, but more studies are needed before it can be declared a safe analgesic.

Conclusions

A patient with cancer pain was treated with LDK infusion, which showed to be efficacious at reducing pain when opioids and standard pain medications were not satisfactory. LDK infusion shows further potential to deliver excellent outcomes in pain management for cancer patients.

Footnote

The patient under observation passed away before informed consent could be obtained. The authors are accountable for all aspects of the work.

Open Access Statement: This article is distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License.