Biosimilars Interchangeability

In the United States, certain biosimilar products may be categorized by FDA as “interchangeable” biosimilars. This means that they may be substituted at the pharmacy without the intervention of the prescriber, much like how generic drugs are routinely substituted for brand name drugs, subject to state or national pharmacy laws.1

How the U.S. Defines Interchangeability

To be designated as an interchangeable biosimilar, FDA must find that the product meets additional requirements beyond the already rigorous requirements for biosimilarity, as outlined by law. The criteria used by FDA to evaluate interchangeability is as follows:2

  • Meets requirements as a biosimilar:
  • Product is highly similar to reference biologic notwithstanding minor differences in clinically inactive components
  • Product has no clinically meaningful differences in quality, efficacy and safety
  • An expectation of producing the same clinical results as the reference biologic in any given patient.
  • The risk in terms of safety or efficacy of switching or alternating between biological products is no higher than using the originator product alone.

As of August 2022, FDA has approved three interchangeable biosimilars.3 The approval of additional interchangeable biosimilars in the United States is expected over the next few years.


  1. USFDA. Biosimilar and Interchangeable Products. 2017.
  2. USFDA. Guidance for Industry: Considerations in Demonstrating Interchangeability With a Reference Product. 2019.
  3. Xcenda. Biosimilar approval and launch status in US. URL: Accessed August 2022.