A biosimilar is a biologic drug that's highly similar to an existing FDA-approved reference product, with no clinically meaningful differences in safety or effectiveness. Biosimilars typically become available after a reference drug's patent protections expire, potentially offering lower-cost alternatives.
Most GLP-1 medications aren't biologics under U.S. law. Exenatide, liraglutide, semaglutide, and tirzepatide are peptides of 40 or fewer amino acids, which the FDA regulates as ordinary drugs (external link), so their lower-cost copies are generics approved through the abbreviated generic-drug pathway, not biosimilars. Those generics have started to arrive: the FDA approved a generic of Byetta (exenatide) in November 2024 and the first generic of Victoza (liraglutide) (external link) on December 23, 2024. Dulaglutide (Trulicity) is the exception. It's a larger fusion protein licensed as a biologic, so a lower-cost copy of it would be a biosimilar.