Differences Between Biosimilars and Generic Drugs

Roy M. Fleischmann, MD: What are the key differences between a biosimilar and a generic small-molecule drug?

Joel M. Gelfand, MD, MSCE, FAAD: That’s a great question. It’s an important nuance. As clinicians, we’ve been used to generic drugs for quite some time. In dermatology, we use a medication called doxycycline for acne, which has other indications. Most of us don’t even think twice about what generic or brand originator is going to be dispensed to the patient. That’s largely because the molecule itself is truly identical, and what varies is maybe the excipients, or the color of the pill, or things of that nature. For the most part, as clinicians, you can usually get away with that with no problem whatsoever.

There may be some unusual circumstances where a patient has an allergy to one of the ingredients in the packaging of the generic medication, or maybe a rare circumstance where the PK [pharmacokinetics] may not be identical for a medication like cyclosporine. But biosimilars aren’t the identical product. They’re nearly identical, especially in the areas that matter the most in terms of where the biologic is binding the target—at the cytokine for example—but there can be some variation in protein structure, glycosylation, and other aspects of the antibody itself.

Roy M. Fleischmann, MD: That’s exactly right. A biosimilar isn’t exactly the same as a generic pill. There are differences between them.

Transcript Edited for Clarity