Nine out of 10 prescriptions are filled by generic drugs — FDA-approved carbon copies of brand-name drugs with expired patents. Over the last 30 years, generic drugs have saved trillions of dollars for hundreds of millions of people.
But newer biologic medicines, including blockbuster treatments for diabetes, cancer, and autoimmune disease, are harder to manufacture into generic form. Unlike traditional “small molecule” drugs made from chemicals, biologics are large, protein-sized molecules made in living cells. Their equivalents, called biosimilars, are close but not identical copies.
Now, a study from UC San Francisco researchers shows that the regulations for biosimilars vary around the world, slowing their development and adoption.
“Just 5% of prescriptions are for biologics like Ozempic, but they make up more than half of all drug spending,” said Jonathan Watanabe , PharmD, MS, PhD, chair of the UCSF Department of Clinical Pharmacy and first author of the paper, which appears in JAMA Health Forum on May 31. “Yet many countries aren’t equipped to quickly vet and approve of new biosimilars, limiting access for patients.”
Generics transformed the prescription drug market in large part because regulators like the U.S. Food and Drug Administration (FDA) lean on the records of brand-name drugs to approve them. But biosimilars, which can vary from the original biologic, aren’t afforded the same streamlined process.
Watanabe and his colleagues dug into biosimilar regulations across 19 countries, including the U.S., Canada, United Kingdom, Nigeria, Brazil, Egypt, and Indonesia. Most countries used similar language to describe biosimilars at first, but their rules for approving them quickly diverged.
Some countries were comfortable approving biosimilars if they were “similar enough” to the biologic in laboratory tests, while others demanded more testing in patients. Some authorized pharmacists to substitute a biosimilar for a biologic at the pharmacy counter, while others required the prescribing doctor to approve or write a new prescription. And some were open to using data and studies from trusted foreign regulators, while others required companies to repeat studies locally.
The researchers say that aligning biosimilar approval across countries could make it easier for biosimilars to reach the market — and hopefully lower costs for all patients, just like generics.
“Generics represent one of the biggest success stories of the pharmaceutical industry in terms of making life-extending treatments more affordable, and we hope our study helps biosimilars do the same,” Watanabe said.
Authors: Other UCSF authors are Michael W. Strand, MS, and Minal Walvekar, MS.
Other authors are Rafael Alfonso-Cristancho, MD, MSc, PhD (GSK).
Funding: This work was funded by GSK (GlaxoSmithKline).
About UCSF: The University of California, San Francisco (UCSF) is exclusively focused on the health sciences and is dedicated to promoting health worldwide through advanced biomedical research, graduate-level education in the life sciences and health professions, and excellence in patient care. UCSF Health , which serves as UCSF’s primary academic medical center, includes top-ranked specialty hospitals and other clinical programs, and has affiliations throughout the Bay Area. UCSF School of Medicine also has a regional campus in Fresno. Learn more at ucsf.edu or see our Fact Sheet .
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JAMA Health Forum
10.1001/jamahealthforum.2026.1642
Literature review
Not applicable
Regulatory Definitions and Classification of Biosimilar Medications Across the 6 Regions of the World Health Organization
31-May-2026
None reported.