The Biosimilar Approval Pathway for GLP-1 Drugs, Explained
Because semaglutide and tirzepatide are peptides, follow-on competitors go through the biosimilar pathway, not the small-molecule generic pathway. Here's the difference.
By the GLP Semaglutide editorial team · Last updated October 25, 2025
Small-molecule generic drugs are approved by demonstrating bioequivalence to the reference product — a relatively streamlined process. Biosimilars, which apply to complex biologic and peptide molecules, require demonstrating no clinically meaningful difference in safety, purity, and potency, a more extensive comparability process.
Why this matters for GLP-1 competition
The biosimilar pathway generally takes longer and costs more to complete than the small-molecule generic pathway, which is one reason analysts expect a slower, more gradual arrival of lower-cost GLP-1 competition compared with a typical small-molecule patent expiration.
Interchangeability is a separate designation
Even after biosimilar approval, a product may need a separate 'interchangeable' designation before a pharmacist can substitute it for the reference product without prescriber sign-off in many jurisdictions — another step beyond basic biosimilar approval.
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