Nephrotoxicity of Combined Tramadol and Alcohol Exposure in Rats: A Scoping Review

Background Tramadol, a widely abused opioid analgesic, is frequently co-consumed with alcohol, particularly among youth in West Africa and other regions. Both substances individually induce oxidative stress and organ damage, yet their combined nephrotoxic potential in preclinical models remains poorly understood. Objective To map the existing evidence on renal biochemical and morphological effects of tramadol–alcohol co-administration in rats and identify research gaps. Methods Scoping review conducted in November 2025. PubMed, Scopus, Web of Science, Google Scholar and regional databases were searched with phrases that included tramadol, alcohol/ethanol, kidney/renal, and rat(s). Eligibility was based on original rat studies with concomitant tramadol and alcohol administration and at least one kidney outcome (biochemical or histological). Screening and data extraction were completed independently. Results Only two of the 83 identified studies matched the inclusion criteria. Ekam et al. (2025) found significant elevations in urea and creatinine, electrolyte abnormalities, and severe histological lesions (glomerular atrophy, tubular collapse) after 21 days of tramadol co-administration with gin or lager beer. Oyewo et al. (2021) found systemic oxidative stress and inflammation after tramadol-alcohol exposure, which has indirect implications for kidney injury. No more rat studies have directly addressed the combined renal consequences. Conclusion The evidence is quite limited, with only two preclinical research globally demonstrating that tramadol-alcohol co-administration causes additive or synergistic nephrotoxicity in rats. Major deficiencies include a lack of dose-response data, long-term trials, mechanistic investigations, and female rat models. Dedicated renal-focused co-exposure research is urgently required to improve toxicological risk assessment and clinical awareness.