- The Food and Drug Administration on Thursday released final guidance on how to name biologic and biosimilar drugs, giving clarity to the industry after a lengthy regulatory process.
- The guidance cements the practice of attaching a meaningless four-letter suffix to the nonproprietary names of both biologics and biosimilars — an effort designed to help distinguish between the two types of drugs.
- While seemingly trivial, the new naming convention is designed to aid pharmacovigilance and prevent inadvertent substitution between biologics and biosimilars, which, unlike generics, are not chemically identical to the drug they reference.
While only four biosimilar drugs are currently approved in the U.S., dozens more are in pipelines and the field looks set to grow dramatically as more aging biologics come off patent.
The anticipated growth is one reason why the FDA's action takes on more importance, despite the dullness of a regulatory document about suffixes.
Since biosimilars are each slightly different than the reference biologic, the FDA has to date added on four extra letters to the end of each non-proprietary name. Filgrastim, the biologic drug Neupogen, becomes filgrastim-sndz, biosimilar Zarxio. Adalimumab (Humira) becomes adalimumab-atto (Amjevita).
The new guidance formalizes that practice and sets new guidelines, declaring each suffix must consist of four lowercase letters and be devoid of meaning.
Whether or not the suffix would contain some meaning had been a point of contention between the FDA and industry. Trade associations PhRMA and BIO had both pushed for the suffixes to be meaningful, such as containing letters suggestive of the biosimilar drugmaker.
Notably, the guidance applies to currently licensed biologic drugs as well, not just biosimilars. For now, the FDA plans to assign suffixes to a limited group of already approved biologics and is considering a process for implementing the new naming convention across all biologics.
Nonproprietary names also play an important role in prescribing and monitoring adverse events, and the guidance aims to address concerns on those fronts.
All four biosimilars currently approved are not considered "interchangeable" with their reference biologic, meaning pharmacists cannot choose to dole out the biosimilar in place of the biologic — a common practice with generics and small-molecule drugs. A suffix helps differentiate the products and avoid inadvertent substitution.
Flagging which drugs are made by separate biosimilar drugmakers should also help facilitate the tracking of product-specific adverse events.
The FDA hopes adding suffixes to all biologic drugs will ensure biosimilars aren't perceived as inferior to their reference products.