Interchangeable Biosimilar
A biosimilar that meets a higher FDA standard, allowing pharmacists to substitute it for the reference biologic without prescriber approval — like a generic drug swap.
How It Works
To earn interchangeable status, a biosimilar manufacturer must demonstrate that patients can switch back and forth between the biosimilar and the reference drug with no additional risk. This requires additional switching studies beyond what's needed for standard biosimilar approval. Interchangeable biosimilars can be substituted at the pharmacy counter without calling the prescriber, just like a generic drug. This designation is expected to accelerate biosimilar adoption because it removes the prescriber as a gatekeeper. Pharmacists check the FDA Purple Book for current interchangeable designations.
Related Terms
- Biosimilar — A biologic product that is "highly similar" to an already approved reference biologic, with no clinically meaningful differences in safety, purity, or potency.
- Biologic Drug — A complex medication derived from living cells — including monoclonal antibodies, vaccines, and cell therapies — that treats serious conditions like cancer and autoimmune diseases.
- Generic Drug — A medication that contains the same active ingredient, dosage, and form as a brand-name drug, approved after the original's patent expires — typically costing 80-95% less.
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About This Definition
This definition is part of the DrugPrice Drug Pricing Glossary — 34 terms explaining how prescription drug pricing works in the United States. All definitions are written in plain language for patients, caregivers, journalists, and healthcare professionals.