This bill deems all biosimilars licensed by the Food and Drug Administration (FDA) interchangeable with their reference products.

A biosimilar is a biological product (e.g., a drug or vaccine) that is very similar to a brand-name biological product (i.e., the reference product). Under current law, a biosimilar that meets additional requirements may be deemed interchangeable with the reference product; this designation allows pharmacists to substitute the interchangeable biosimilar when filling a prescription for the reference product, depending on state law. Further, the first biosimilar deemed interchangeable with a given reference product is awarded a period of marketing exclusivity.

The bill eliminates additional requirements for demonstrating interchangeability so that all licensed biosimilars are deemed interchangeable with their reference products. (Draft guidance released by the FDA in 2024 proposed to make some of these interchangeability requirements optional, including studies related to the safety of switching between use of the biosimilar and reference product. It has not been finalized.)

This change takes effect 60 days after the bill is enacted, and previously licensed biosimilars must be deemed interchangeable with their reference products on that date. However, the bill preserves the exclusivity period for first interchangeable biosimilars licensed before the bill’s enactment. For example, if a new biosimilar licensed after the bill takes effect relies on the same reference product as an existing biosimilar that is subject to an unexpired exclusivity period, the new biosimilar is not deemed interchangeable with the reference product until the exclusivity period has ended.