What is a biosimilar and how is it different from a generic drug?

A biosimilar is a biologic product highly similar to an already-approved reference biologic, with no clinically meaningful differences in safety, purity, or potency. Unlike generics (exact copies of small molecule drugs), biosimilars cannot be identical due to the complexity of biologics and manufacturing variability. Biosimilar approval requires: analytical similarity studies (structure, function), animal studies (toxicity), and clinical studies (pharmacokinetics, immunogenicity, efficacy). The regulatory pathway is abbreviated compared to new biologics but more rigorous than generics. Biosimilars offer cost savings (15-30% less than reference products) and increased patient access. Examples include biosimilar adalimumab (Humira), trastuzumab (Herceptin), and insulin glargine.