Biochemical Toxicity Induced By Tramadol Administration In Male Rats

Introduction: Tramadol is a centrally acting analgesic used for treatment of moderate to severe pain. There has been some controversy regarding the dependence lability of long- term use of this medication. The present work was conducted to assess the biochemical toxicity profiles of tramadol during therapeutic use. Liver and kidney functions, sex hormones activity and some metabolic parameters were studied in male rats.  Methods: Rats were divided into three groups. Group one received vehicle (saline), group two and three received oral doses of tramadol equal to 40 mg and 80 mg / kg body weight / day respectively for a month followed by 10 days recovery period. Biochemical measurements were carried out every 10 days.  Results: There was significant increase in the levels of serum aminotransferases (ALT,AST), lactate dehydrogenase (LDH), urea nitrogen (BUN),creatinine and lipid peroxide ( MDA) in both tramadol groups. In contrast, serum glucose, total cholesterol and triglycerides were significantly reduced. Tramadol significantly reduced serum luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone and cortisol, but elevated prolactin (PRL) and estradiol (E2) in male rats specially at 20 and 30 days of treatment. After 10 days recovery, 80 mg tramadol group remained significantly different compared to control one.  Conclusion:The present finding pointed out the risk of increased lipid peroxidatin, hepatic and renal damage and sexual dysfunction. Tramadol toxic effects should be kept in mind during long term therapy specially in large doses.