What to Know about FDA’s Revised Peptide Guidance

What Manufacturers Need to Know

Seventeen revised draft product-specific guidance documents reflect FDA’s evolving scientific and regulatory approach to generic peptide drug development.

On July 28, 2026, the U.S. Food and Drug Administration (FDA) published 17 revised draft product-specific guidances (PSGs) addressing the development of generic peptide drugs, including products used to treat diabetes, obesity, osteoporosis, and macular degeneration.

The revisions reflect advances in analytical science, manufacturing technology, and regulatory experience with complex peptide products. They also provide updated recommendations for manufacturers seeking approval through the abbreviated new drug application (ANDA) pathway.

Unlike many conventional small-molecule drugs, peptide products can present additional challenges involving molecular structure, manufacturing-related impurities, and biological activity. These characteristics can complicate the demonstration that a proposed generic product is equivalent to its reference listed drug.

FDA’s revised guidances address five important areas of generic peptide development.

Five Areas of Regulatory Focus

Peptide Manufacturing and ANDA Eligibility

The revised guidances address the submission of ANDAs for peptides manufactured using recombinant, synthetic, or semisynthetic production methods. These recommendations are particularly relevant when the proposed generic and reference products are manufactured using different technologies.

Innate Immune Response Testing

Peptide products may present immunological concerns that require evaluation. FDA’s updated recommendations address testing related to innate immune responses, an important consideration when assessing product quality and potential safety risks.

Impurity Thresholds

Peptide manufacturing can produce impurities that differ depending on the manufacturing process. The revised guidance documents address impurity thresholds, providing recommendations relevant to impurity characterization, evaluation, and control during generic product development.

Higher-Order Structure Assessment

The three-dimensional structure of a peptide can influence its biological properties. FDA’s recommendations address higher-order structure assessment as part of the scientific evaluation of certain generic peptide products.

Biological Activity Assessment

Demonstrating appropriate biological activity is another important consideration in evaluating peptide products. The revised guidances address biological activity assessments that may contribute to demonstrating equivalence between proposed generic products and their reference drugs.

Together, these five areas illustrate FDA’s emphasis on scientific characterization and evidence-based assessment of complex peptide products. The specific recommendations and supporting evidence will depend on the individual product and its applicable guidance.

FDA Withdraws Earlier Peptide Guidance

Alongside the revised PSGs, FDA withdrew its May 2021 guidance, ANDAs for Certain Highly Purified Synthetic Peptide Drug Products That Refer to Listed Drugs of rDNA Origin, stating that it no longer reflects the agency’s current scientific thinking.

FDA also indicated plans to revise that guidance in 2026.

The withdrawal is particularly relevant for manufacturers whose development strategies relied on the earlier recommendations. Those manufacturers should review the updated product-specific guidance and evaluate whether changes to their development or submission strategies are appropriate.

Implications for Generic Peptide Developers

The revised draft guidances provide an opportunity for manufacturers to reassess their analytical, manufacturing, and regulatory strategies before submitting an ANDA.

Manufacturers developing affected peptide products should consider whether their existing programs adequately address the applicable recommendations for impurity characterization, structural assessment, biological activity, and immunological evaluation.

The recommendations may also have implications beyond the 17 products specifically identified. FDA encourages developers of other generic peptide products to consult its Office of Generic Drugs through formal meetings or controlled correspondence when these recommendations may be applicable.

Importantly, the revised guidances remain in draft form. Manufacturers should distinguish FDA’s proposed recommendations from finalized guidance and applicable regulatory requirements when making development decisions.

Products Covered by the Revised Draft Guidances

The 17 revised draft PSGs address nine peptide ingredients, several of which have multiple reference listed products.

Manufacturers can review the individual recommendations through FDA’s Product-Specific Guidance Database.

Looking Ahead

FDA’s latest revisions underscore the increasing importance of advanced analytical methods and product-specific scientific evidence in generic peptide development.

For manufacturers, the central consideration is not simply whether a peptide can be produced using a particular manufacturing method, but whether the proposed generic product can be adequately characterized and demonstrated to meet applicable requirements for quality, safety, and effectiveness.

As FDA continues refining its approach to complex generic products, manufacturers that evaluate these expectations early in development will be better positioned to identify regulatory gaps, plan appropriate studies, and prepare scientifically supported submissions.