And the Answer Is...

Answer: Clinically inactive components

Biosimilars must show no clinically meaningful differences in efficacy and safety compared with their biologic reference products. The doses, route of administration, and mechanism of action must also be similar. Only minor differences in clinically inactive components are permitted.

That might be common knowledge to pharmacists, but surveys show that some primary care physicians have had little exposure to biosimilars and don't fully understand what they are or how the US Food and Drug Administration (FDA) approves them for use, according to Dr. Jim Stevenson, the chief pharmacy officer at the University of Michigan Hospitals and Health Centers and the president of hospital and health services for Visante, a pharmacy consulting firm based in St. Paul, Minnesota.

Dr. Stevenson said pharmacists are well positioned to improve a provider’s baseline understanding of how biologics differ from small molecule drugs and how the FDA’s abbreviated biosimilar approval process works. He also said pharmacists could help clear up misconceptions prescribers might have about the scope and degree of physicochemical analysis, factors which limit the set of clinical studies designed to demonstrate biosimilarity between a proposed biosimilar and its reference product.

Moving forward, Dr. Stevenson said clearer regulations regarding pharmacist-led substitution of interchangeable biosimilars are needed, and practical barriers related to the proposed naming convention of biosimilars must also be solved. While the FDA has currently approved only 2 biosimilars — infliximab-dyyb (Inflectra) and filgrastim-sndz (Zarxio) — many more are in the pipeline that should have significant impact on overall pharmaceutical spending in the coming years, said Dr. Stevenson.

—Dan Cook