Naming Convention, Interchangeability, and Patient Interest in Biosimilars

Although biosimilars may offer cost savings over their comparable biologics, use of biosimilars in the United States remains relatively low. This study investigates two barriers to uptake of biosimilars in the United States. First, the U.S. Food and Drug Administration requires that four-letter suffixes be added to the nonproprietary names of all biosimilars, as well as to the nonproprietary names of all biologics approved after March 2020. Second, biosimilars are not interchangeable with their reference biologic product at the pharmacy counter; a new prescription is needed for the biosimilar to be dispensed in place of the biologic. We conducted two behavioral experiments to examine the effects of the naming convention and interchangeability designation on patients’ interest in biosimilars. We found that, absent the mention of needing a new prescription, adding four-letter suffixes to biosimilars’ nonproprietary names decreased participants’ likelihood of using the biosimilars. When participants were told whether a biosimilar required a new prescription, they were more interested in the biosimilar when it did not require a new prescription, and this effect was driven by participants’ perceived similarity of the biosimilar to the biologic. The effect of interchangeability dominated the suffix effect. Our results suggest that both biosimilar suffixes and interchangeability issues provide signals to patients regarding the perceived similarity of biosimilars to their reference biologics and influence patient usage of biosimilars.