A biosimilar product is a biological product that is highly similar to and has no clinically meaningful differences in terms of safety or effectiveness from an existing FDA-licensed (approved) reference product.

An interchangeable product is a biological product that meets the requirements for a biosimilar product and is approved based on information that is sufficient to show that it can be expected to produce the same clinical result as the reference product in any given patient; and for a biological product that is administered more than once to an individual, there is not a greater safety risk or risk of reduced efficacy from alternating or switching between use of the interchangeable product and its reference product. An interchangeable product can be substituted for the reference product without the intervention of the prescribing health care provider.

A reference product is the single biological product, already licensed (approved) by FDA under section 351(a) of the Public Health Service Act, against which a proposed biosimilar or interchangeable product is compared. A reference product is approved based on, among other things, a full complement of safety and effectiveness data. A biosimilar or interchangeable product is licensed (approved) by FDA under section 351(k) of the Public Health Service Act. A proposed biosimilar or interchangeable product is compared to and evaluated against a reference product to ensure that the proposed product is highly similar to, and has no clinically meaningful differences from, its reference product.