Tramadol is an analgesic used to treat moderate to severe pain caused by cancer, osteoarthritis, and other musculoskeletal diseases. Cytochrome P450 system metabolizes tramadol and induces oxidative stress in different organs. Therefore, the present study aims at investigating the changes in the activities and the protein expressions of CYPs isozymes (2E1, 3A4, 2B1/2), antioxidants status, free radicals levels after pretreatment of rats with Curcumin and/or Gallic as single- and/or repeated-doses before administration of tramadol. In repeated-dose treatments of rats with tramadol, the activities of cytochrome P450, cytochrome b5, and NADPH-cytochrome-c-reductase, and the antioxidant enzymes including glutathione reductase, glutathione peroxidase, glutathione S-transferase, catalase, superoxide dismutase, and levels of glutathione were inhibited in the liver and the kidney of rats. Interestingly, such changes caused by tramadol restored to their normal levels after pretreatment of rats with either Curcumin and/or Gallic acid. On the other hand, repeated-dose treatment of rats with tramadol increased the activities of both dimethylnitrosamine N-demethylase I (DMN-dI), and aryl hydrocarbon hydroxylase (AHH) compared to the control group. However, pretreatment of rats with Curcumin and/or Gallic acid prior to administration of tramadol restored the inhibited DMN-dI activity and its protein expression (CYP 2E1) to their normal levels. On the other hand, tramadol inhibited the activity of ethoxycoumarin O-deethylase (ECOD) and suppressed its protein marker expression (CYP2B1/2), whereas Curcumin, Gallic acid and/or their mixture restored such changes to their normal levels. In conclusion, Curcumin and/or Gallic acid alleviated the adverse effects caused by tramadol. In addition, patients should be advice to take Curcumin and/or Gallic acid prior to tramadol treatment to alleviate the hepatic and renal toxicities caused by tramadol.
