Biosimilar
A biologic drug highly similar to an already-approved reference product, with distinct promotional and substitution rules.
A biosimilar is a biologic drug shown to be highly similar to an already-approved reference biologic, with no clinically meaningful differences in safety, purity, or potency. It's approved through an abbreviated pathway that relies in part on the reference product's existing safety and efficacy data, rather than requiring a full clinical program from scratch. That makes it different from a generic, which is a straightforward copy of a small-molecule drug. Biologics are too structurally complex to copy exactly, so "similar" is the standard, not identical.
That similarity standard shapes what a biosimilar can claim. It can point to the reference product's established efficacy, but substitution rules, whether a pharmacist can swap one for the other without the prescriber's involvement, depend on an additional interchangeability determination and vary by jurisdiction. Promotional content needs to be specific about which status actually applies to the product it's describing.