The FDA has spoken on biosimilar names. But will its hybrid proposal work?

After much industry lobbying and public debate, the FDA has proposed a system for naming biosimilar drugs. It's a sort of hybrid of the generic name on one hand and the unique brand name on the other. And it would allow the FDA to make some biosims easy to substitute for the brand-name original--and others not so easy.

Under the FDA's plan, both branded meds and biosims would share a "core drug substance" name. Each product would also carry a four-letter suffix. Those suffixes could be individualized product-by-product, to allow a Merck & Co. ($MRK) biosimilar, for instance, to be differentiated from an Eli Lilly ($LLY) biosimilar of the same product. Under the FDA proposal, the suffixes wouldn't be derived from the manufacturer's name, however.

Drugs with varying suffixes wouldn't be automatically interchangeable. That might seem to be a victory for branded drugmakers, who've been working to limit quick-and-easy substitution of biosims for their brands.

But copycat drugmakers shouldn't fret too much. The FDA is asking for comment on a different approach for biosims it deems interchangable. For such drugs, biosims might share the same suffix as the brand. Like garden-variety generics that share nonproprietary names with brands--Novartis' ($NVS) Diovan and its generic copies valsartan, for instance--these biosims would be easily substituted for their more expensive original counterparts.

That approach would allow the FDA not only to restrict easy substitution of biosims for particular reference products. It would theoretically allow the agency to pick and choose among individual biosims. So, the FDA could decide that one particular copycat drug qualifies as interchangeable with the brand, but the rest of the biosims of that same brand don't.

The biosimilar naming conventions have been a hot topic for years as the FDA has set up its pathway for approving knockoff versions of biologic treatments. Biosimilar developers naturally want their copies to be easily substituted for the brand-name products. Payers concur, because they're looking for as many savings as possible, and easy substitution of the less-expensive copies means lower costs. The branded drugmakers, however, want to preserve their sales, so quick-and-easy subbing isn't welcome there.

And then there are worries about medication errors and safety. The FDA's naming proposal aims to address both, the agency said in a Thursday blog post: preventing inadvertent substitution of products the FDA doesn't consider interchangeable, and allowing the agency and drugmakers to track individual biosims and any safety problems that might crop up.

We'll see how the industry responds as comments on the naming proposals roll in. Expect some lively debate: Tens of billions in sales are at stake for biologic drugmakers and their biosim rivals.

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