> ## Content Index
> Fetch the complete content index at: https://www.fdaweb.com/llms.txt
> Use this file to discover other available public pages before exploring further.

# Biosimilar Interchangeable Guidance Analysis
- URL: https://www.fdaweb.com/biosimilar-interchangeable-guidance-analysis/
- Published: 2017-03-01T12:00:00.000Z
- Updated: 2026-09-14T22:09:22.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5138094

Three Mayer-Brown attorneys say that a recent FDA [draft guidance](https://www.fdaweb.com/draft-guide-on-biosimilar-interchangeability/) on the standards for demonstrating interchangeability of biosimilar products “is a significant step forward in FDA’s progress toward full implementation of the regulations required by the Biologics Price Competition and Innovation Act (BPCIA).” Writing in a [Legal Update](https://www.mayerbrown.com/files/Publication/7f488d44-a9a1-446d-987d-808e713b6663/Presentation/PublicationAttachment/d2eb35c1-cd15-47a7-8552-621b1ff48b9d/170125-UPDATE-IP-LifeSci.pdf?ref=fdaweb.com), the attorneys say the guidance provides a detailed and yet relatively flexible set of observations and recommendations for the process by which a sponsor can establish a biosimilar as interchangeable.

The agency said that it generally intends to follow the “totality of the evidence” and “residual uncertainty” approaches that it has taken in earlier guidances addressing quality considerations, scientific considerations, and questions and answers for biosimilarity under the BPCIA, the update says. The attorneys explain that the agency has said it recognizes that the type of data submitted may vary depending on the nature of the proposed interchangeable product. The information may include evaluation of quality attributes, analytical differences in the molecules, mechanisms of action, biodistribution in differing patient populations, and toxicities.

“Where there are differences in these parameters,” the analysis says, “FDA will require the sponsor to establish a scientific justification for why such differences do not preclude a showing of interchangeability. FDA tempers that requirement by allowing for the possibility of extrapolation for certain of the data supporting a demonstration of interchangeability.”

The analysis reviews product-dependent factors, impact of biosimilar product postmarketing data, switching study design considerations, extrapolation of data, use of a reference product in switching studies, presentations for interchangeable products, and postmarketing safety monitoring.

“Not surprisingly, given the complexity and relative novelty of the subject,” the authors conclude, “FDA repeats throughout the draft guidance that sponsors should consult with FDA on these issues early and often.”