What are the differences between biosimilar and interchangeable?

When biologics’ patents expire, other companies can launch similar products and lower costs. However, most biologics are more complex than small molecule drugs in structure, and are more difficult to characterize. Of course, the clinical uses of similar biologics are more complex.

The FDA divides similar products into biosimilar and interchangeable. Biosimilars are highly similar to the reference product, and have no clinically meaningful differences from the reference product. An interchangeable product, in addition to meeting the biosimilar standard, is expected to produce the same clinical result as the reference product in any given patient.

In other words, both biosimilars and interchangeable products have allowable differences from the reference product because they are made from living organisms, but have no clinically meaningful differences. The interchangeable standard is stricter. In addition to demonstrating clinical similarity, interchangeable product manufacturers have to demonstrate that product switching doesn’t increase risk.

According to the latest draft guidance, titled “Nonproprietary Naming of Biological Products”, the reference product and biosimilars would share a “core drug substance” name and would also carry a distinct four-letter suffix for each product (e.g., replicamab-cznm, replicamab-hixf). Interchangeable products may share the same suffix as the reference product.

That approach would restrict easy substitution of biosimilars for the reference product. An interchangeable product can be substituted for the reference product by a pharmacist, even if the physician writes the prescription for the reference product. However, a biosimilar should be prescribed by a physician (the physician has to write the specific name of the biosimilar).


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