IFNA2 and respiratory tract infectious disorder: This study aimed to evaluate the safety profile and toxicokinetic (TK) characteristics of pegylated interferon α-2b (PEG IFNα-2b) following repeated nebulized inhalation exposure in juvenile Sprague-Dawley (SD) rats, and to establish the no-observed-adverse-effect level (NOAEL) to support its clinical development for pediatric respiratory infections.