Renal Biomarker and Histological Effects of Salbutamol, Montelukast, Prednisolone, and their Combination in Asthmatic Rats

Introduction: Asthma is a chronic inflammatory disorder increasingly recognized as a systemic disease with oxidative and metabolic consequences extending beyond the airways. The kidney, a key regulator of homeostasis, is particularly vulnerable to oxidative and inflammatory injury. Aim: This study investigated the renal effects of salbutamol, montelukast, prednisolone, and the combination of salbutamol/prednisolone in Sprague-Dawley rat model of ovalbumin (OVA)-induced asthma. Methods: Forty-two rats were divided into six groups (n = 7): negative control, positive control (OVA only), montelukast (10 mg/kg/day; oral), prednisolone (3 mg/kg/day; oral), salbutamol (2 mg/kg bd/day oral), and salbutamol/prednisolone (2 mg/kg/day & 3 mg/kg/day orally, respectively). Asthma was induced by intraperitoneal 1 mg OVA and 20 mg aluminium hydroxide sensitization on days 1 & 7 followed by 1 mg w/v OVA aerosol challenge twice weekly for the next 28 days, treatment lasted the period of challenge. Serum renal biomarkers (urea, creatinine, electrolytes, fractional sodium excretion) and kidney tissue oxidative stress parameters [malondialdehyde (MDA), total protein, glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase] were assayed. Histological evaluation was performed on H&E-stained renal sections. Results: Salbutamol, alone or in combination with prednisolone, significantly increased MDA and antioxidant enzyme activities, while reducing total protein, indicating oxidative stress with compensatory upregulation. Serum urea rose in salbutamol-, prednisolone-, and combination-treated groups, whereas creatinine, electrolytes, and sodium excretion remained unchanged, suggesting altered nitrogen metabolism rather than overt dysfunction. Montelukast and prednisolone alone had minimal effects on oxidative markers. Histology confirmed asthma-induced renal inflammation; montelukast provided partial protection, while the salbutamol and salbutamol/prednisolone groups exhibited tubular dilatation and urinary space expansion. Conclusion: Conclusively, salbutamol, particularly in combination with prednisolone, exacerbates renal oxidative stress and structural alterations, whereas montelukast appears neutral or modestly protective. These findings emphasize the importance of renal monitoring during asthma therapy and support the evaluation of adjunct antioxidant strategies.