Plasma antioxidant state in patients undergoing long-term opioid treatment

Background: Opioid treatment is now an integral part of pharmacotherapy for severe chronic malignant and non-malignant pain. Currently, there is a sufficient selection of opioids to allow individualized pain treatment. Several experimental studies have confirmed the effect of opioids on oxidative stress. The aim of this work is to determine the presence of redox changes occurring as a result of long-term opioid use in patients with chronic pain. Results: Six months of opioid use for severe pain was evaluated in 37 patients. Patients formed three groups depending opioid treatment (oxycodone, fentanyl and tapentadol) and were compared with 42 healthy probands. Compared to control, activities of superoxide dismutase were decreased, while those of glutathione peroxidase and glutathione reductase were significantly increased in all groups. Together with lowered levels of reduced glutathione, this indicated conditions of oxidative stress. There were no differences between treatment groups. Conclusion: It is necessary to know the risks of side effects and provide patients with possible solutions. At this stage and with this number of subjects, we can condude that neither the form of administration nor the type of opioid has any effect on reducing oxidative stress from opioid metabolism in the treatment of severe pain.