; Contrast media; Iohexol; Urographin; nephrotoxicity; hepatotoxicity; Wistar rats; Kruskal–Wallis; histopathology.

Background: Radiographic contrast agents are widely used for diagnostic enhancement, yet concerns remain about their toxic effects on vital organs. Statement of Problem: Despite the popularity of contrast media as a radiological technique, the possible systemic and organ-level impact of this method has not been properly examined, particularly in Nigeria. Thus, the research assesses and contrasts the biological effects of selected contrast agents use in Wistar-rats so as to support the evidence that can be used to guide the use of safer contrast media that is evidence-based. Aim: This experimental study compared the biochemical, histopathological, and behavioral effects of ionic (Urographin) and non-ionic (Iohexol) contrast media on Wistar rats. Methods: Nine rats were randomized into three groups: control, Urographin, and Iohexol. Kidney and liver markers, body weight, and behavior were assessed, followed by histological evaluation. Results: Urographin produced higher renal stress, with urea increasing from 36.4 to 41.3 mg/dL (+13.5%) and creatinine rising from 3.98 to 4.15 mg/dL (+4.3%) compared to Iohexol (urea 40.1 mg/dL, +10.2%; creatinine 4.05 mg/dL, +1.8%). Kruskal–Wallis analysis showed borderline group differences for creatinine (p = 0.0628), sodium (p = 0.0628), and potassium (p = 0.0594), while other renal markers were not statistically significant (p > 0.05). Hepatic markers showed a marked increase in AST with Urographin (96.9 to 162.5 U/L, +67.7%; p ≈ 0.0665), compared to Iohexol (119.9 U/L, +23.7%), while ALT changes were modest (p > 0.05). Total bilirubin increased by 22.1% in the Urographin group versus 8.6% in the Iohexol group. Body weight declined significantly more with Urographin (−5.8%) than Iohexol (−2.0%), with a borderline statistical trend (p = 0.064). Behaviorally, both agents caused reduced activity, piloerection, and appetite loss, but these signs were more severe in the Urographin group. Histopathology revealed mild hepatitis and pyelonephritis in Iohexol-treated rats, compared to zonal necrosis, vascular congestion, and glomerular degeneration in Urographin-treated rats. Conclusion: Both contrast media induced biochemical and tissue injury, but Urographin demonstrated greater toxic potential. Iohexol may therefore be considered the safer alternative for contrast-enhanced procedures.