Tramadol-Induced Organ Toxicity via Oxidative Stress : A Review Study

Background: Tramadol (TR) is a synthetic opioid-like centrally acting analgesic used for moderate to severe pain management in various diseases. Numerous investigations have supported the association between tramadol use and increased levels of oxygen-free radicals. Mass production of reactive oxygen species produces secondary toxic compounds. This could damage the internal components of the cell and ultimately causes organ damage. There exists a growing trend of tramadol abuse and the increasing reports of poisoning, abuse, and mortality due to this drug. Thus, the present study aimed to review the animals and human studies on the effects of acute and chronic exposure of tramadol in inducing organ toxicities through oxidative stress. Methods: Pubmed, Google Scholar, and Scopus bibliographic databases were searched for studies that investigated oxidative stress as a mechanism of toxicity by tramadol. A manual search of reference lists of the retrieved articles was conducted. Data were collected from 2000 to 2021 (up to June 2021). Results: From 28 articles concerning experimental and human studies of TR-induced oxidative stress organ damage, which included in this review, the occurrence of lipid peroxidation, alteration in the levels of total antioxidant capacity, and other oxidative stress biomarkers in many organs such as the brain, liver, kidney, adrenal and lung in the experimental studies of tramadol exposure have been observed. Conclusion: Oxidative stress could be considered the most critical toxic mechanism in TR-induced tissue damage.