Definition: A biosimilar is a biologic medicine that is highly similar to a biologic FDA has already approved, called the reference product, and has no clinically meaningful differences from it. FDA says you can expect the same safety and effectiveness over the course of treatment as with the reference product.
Biologics are made from living sources such as cells or microorganisms, rather than built by chemistry. FDA says biosimilars are made from the same types of sources as their reference products. Because they come from living systems, the standard is "highly similar" with no clinically meaningful differences, rather than the identical active ingredient required of a generic drug.
An interchangeable biosimilar meets extra requirements so a pharmacist may substitute it without asking the prescriber. FDA calls this pharmacy-level substitution and notes that it is subject to state law. FDA says biosimilars and interchangeable biosimilars are as safe and effective as the original product, and that a biosimilar is not safer or more effective than it either.
Several medicines on this site are biologics, such as somatropin and epoetin. Each product has its own label, device and storage rules. If a pharmacy switches you to a different product, log it as a new medicine or vial so your history shows the change and you can check the new label for its storage and mixing steps.
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