Biologic drugs have revolutionized disease management for many serious and chronic conditions including cancer, rheumatoid arthritis, Crohn’s disease, and psoriasis.1Versions of biologic drugs, known as biosimilars, have helped improve access to these critical medicines for a wider patient population and lowered healthcare costs.2

As biosimilars continue to hit the market in greater numbers, you’ll be hearing more about this class of drugs, as well as the “interchangeability” designation that some biosimilars receive.

Here are five things you need to know about interchangeability.

1. Some biosimilars have an additional regulatory designation called interchangeability

In the U.S., a biosimilar with an “interchangeable” designation can be substituted for its reference product at the pharmacy, without additional approvals from the prescribing physician, state law permitting.  Sound familiar? This is similar to the way that a pharmacist can substitute a generic medicine for a branded drug when filling a prescription.

To achieve an interchangeable designation, clinical studies are conducted to demonstrate that there is no additional risk or reduced drug effectiveness if a patient switches back and forth between an interchangeable biosimilar and a reference product, as compared to receiving treatment with just the reference product.3

These switching studies are conducted in addition to the rigorous approval process that all biosimilars undergo to meet the exacting FDA standards for biosimilar safety and efficacy.4

2. Interchangeability remains the exception, not the rule, when it comes to biosimilars.

The Biologics Price Competition and Innovation Act (BPCIA), which was enacted in 2010, allowed an interchangeability designation for FDA-approved biosimilars that met additional requirements 5.

As of October 2022, three biosimilars had received interchangeability status: an insulin product6, a drug used to treat certain inflammatory diseases,7 and a treatment for retinal patients.8 Eventually, there may be more. Other pharmaceutical companies have submitted applications seeking interchangeability status for biosimilars to a biologic medicine used to treat certain inflammatory conditions.

3. An interchangeability designation is unique to biosimilars in the U.S.

Although biosimilars are among the fastest growing products in the prescription drug industry, real-world experience with interchangeability is in its infancy, and therefore different countries have different regulatory approaches. For example, a separate regulatory designation for interchangeability has been instituted in the U.S.9,10,11

In the European Union, which introduced and adopted biosimilars before the U.S. did, the decision of allowing interchangeability for biosimilars lies with each member state.12 And in Japan and Iran, interchangeability is not a separate designation, but is automatically applied when the biosimilar is approved.13 Similarly, the standards for regulatory review of biosimilars may also vary.

4. Interchangeability is granted at the federal level but governed by state laws

Biosimilars receive an interchangeability designation on a federal level from the FDA, but the local dispensing and substitution of drugs at the pharmacy level is governed by state laws. The majority of states allow biosimilars to be substituted for a biologic medicine, with varying degrees of notification to the prescribing physician and the patient.  As of May 2019, 45 states and Puerto Rico allow substitution of a biosimilar for a biologic medicine.14

5. Interchangeability is significant for medicines dispensed at the pharmacy

Biologics (and biosimilars) are typically administered either by injection or intravenously. Generally, those administered by an injection are dispensed from a pharmacy and may be self-administered, while biologic medicines that are administered intravenously are often given by a healthcare professional.12, 14

So, for patients who receive their biologic from a pharmacy, a reference product may be substituted with an interchangeable biosimilar, which may provide cost-savings.6

This article is for informational purposes only and is not intended to provide legal advice.


  1. Adami, G., Saag, K.G., Chapurlat, R.D., et al. Balance benefits and risks in the era of biologics. Ther Adv Musculoskelet Dis. 2019 Oct 24;11:1759720X19883973. doi: 10.1177/1759720X19883973
  2. Biosimilar product information. U.S. Food and Drug Administration. Last updated February 25, 2022. Accessed March 28, 2022.
  3. Prescribing Interchangeable Products. U.S. Food and Drug Administration. Accessed April 14, 2022.
  4. Biosimilar and Interchangeable Products. U.S. Food and Drug Administration. Published October 23, 2017. Accessed March 31, 2022.
  5. The Patient Protection and Affordable Care Act. U.S. Senate. Accessed March 31, 2022.
  6. FDA approves first interchangeable biosimilar insulin product for treatment of diabetes. U.S. Food and Drug Administration. Published July 28, 2021. Accessed November 17, 2021.
  7. FDA Approves Cyltezo, the First Interchangeable Biosimilar to Humira. U.S. Food and Drug Administration. Published October 18, 2021. Accessed March 28, 2022.
  8. FDA Approves Coherus’ Cimerli as Interchangeable Biosimilar to Ranibizumab. Center for Biosimilars. Published August 2, 2022. Accessed October 12, 2022.
  9. FDA Accepts for Review Pfizer’s Supplemental Application for ABRILADA™ (adalimumab-afzb) Interchangeability. Pfizer. Published February 25, 2022. Accessed March 31, 2022.
  10. Amgen Letter to Shareholders 2021. Amgen. Accessed March 31, 2022.
  11. FDA Accepts Samsung Bioepis’ and Organon’s sBLA for their Citrate-Free, High-Concentration HUMIRA® (Adalimumab) Biosimilar Candidate. Organon. Published January 5, 2022. Accessed March 28, 2022.
  12. The European Medicines Agency and the European Commission. Biosimilars in the EU: Information guide for healthcare professionals. Published 2019. Accessed May 4, 2022.
  13. Ferreri, Deana, PhD. WHO Survey Identifies Global Regulatory Challenges for Biosimilars. The Center for Biosimilars. Published December 3, 2020. Accessed May 16, 2022.
  14. State Laws and Legislation Related to Biologic Medications and Substitutions of Biosimilars. National Conference of State Legislators. Published May 3, 2019. Accessed April 4, 2022.