Wider access to biologic medicines has been made possible by biosimilars, which provide clinically equivalent options at a lower cost. However, robust immunogenicity surveillance and reliable switching and interchangeability pathways are still necessary for real-world use. The "totality of evidence" may be translated into standardized, patient-centered switching and interchangeability pathways that maintain efficacy and safety through pharmacy-led stewardship initiatives. This narrative review was carried out using PubMed/MEDLINE, Embase, Scopus, Web of Science Core Collection, and Google Scholar between 1 January 2019, and 1 December 2025. This review shows that biosimilars and reference biologics are clinically equivalent, and switching typically has no appreciable impact on population-level safety or immunogenicity. However, switching should be supported by a pharmacy-led toolkit that includes risk-stratified immunogenicity testing (event-triggered vs. scheduled), a minimum assay set plus drug levels, and an action algorithm to differentiate PK failure, PD failure, and immune-mediated failure because a small subset of patients may experience clinically significant ADA/NAb-mediated loss of response or tolerability issues. The issue is now to "operate switching safely" rather than "prove switching," since regulatory trends encourage interchangeability and simplify evidence requirements.
Abouhait et al. (Thu,) studied this question.