This guidance is intended to assist potential applicants in determining when an application for a synthetic peptide drug product (synthetic peptide) that refers to a previously approved peptide drug product of recombinant deoxyribonucleic acid (rDNA) origin (peptide of rDNA origin) should be submitted as an abbreviated new drug application (ANDA) under section 505(j) of the Federal Food, Drug, and Cosmetic Act (FD&C Act) rather than as a new drug application (NDA) under section 505(b) of the FD&C Act. Specifically, this guidance provides recommendations for evaluating whether an ANDA submission is appropriate for a synthetic peptide that references any of the following five previously approved peptide drug products of rDNA origin: glucagon, liraglutide, nesiritide, teriparatide, and teduglutide. .