Ketamine Infusion Therapy in chronic pain

Abstract

Background: Ketamine has been used for several years in the treatment of therapy-resistant chronic pain. The effects on multiple receptors that participate in the perception of pain are shown both in vivo and in vitro. Nevertheless, only a few clinical studies, often in relatively small populations, support the efficacy of ketamine in chronic pain.

Objectives: This study aimed to investigate the efficacy of ketamine infusion therapy in a relatively large population at our center. Furthermore, we report the side effects and complications in this population.

Design: Retrospective cohort study.

Setting: General Hospital AZ Sint-Blasius, Dendermonde, Belgium.

Methods: Between January 1, 2015, and December 31, 2019, 74 patients with chronic pain were treated with ketamine infusions at our center. After an initial test dose of 75 mg, patients were treated with 150 mg of racemic ketamine. Forty-five patients were included in the study and were treated according to the protocol. Data were extracted retrospectively from the patient files and analyzed.

Main outcome measures: A favorable outcome was defined as a ≥50% reduction in pain from baseline and when the patient did not discontinue treatment because of lack of effect.

Results: 23/45 (51.1%) had a favorable outcome as defined. No significant difference in efficacy was observed for neuropathic, nociceptive, or nociplastic pain. Side effects were generally mild and easily treated. No major complications related to ketamine infusion therapy were observed in this population.

Conclusions: Overall, the results of this study were positive, especially considering that first- and second-line treatments did not benefit these patients. Ketamine is therefore a valuable therapeutic option for treatment-resistant chronic pain. Further research should include infusions of isolated S-ketamine, which may provide additional benefits regarding its effects and side effects.