If your pharmacy isn’t actively engaged in biosimilar substitution strategy, you are leaving money on the table in one of the fastest-growing financial opportunities in all of pharmacy. The savings data released this month makes the business case undeniable, and the regulatory environment has never been more favorable for pharmacist-led action.
The Numbers That Should Stop Every Pharmacist Mid-Scroll
Biosimilars generated $20.2 billion in savings in 2024 alone, and $56.2 billion since the first biosimilar entered the U.S. market in 2015. Generic and biosimilar medicines collectively saved the U.S. healthcare system $467 billion in 2024, contributing to nearly $3.4 trillion in savings over the preceding decade.
Since 2015, biosimilars have been used in approximately 3.3 billion days of patient therapy with no unique clinical challenges. Biosimilar competition has expanded patient access by nearly 460 million incremental days of therapy; care patients would not have received otherwise under reference biologic pricing.
More than 90 biosimilars have received FDA approval to date, and nearly 25 additional products are expected within the next two years. High-cost oncology biologics now facing biosimilar competition include ipilimumab (Yervoy), pertuzumab (Perjeta), pembrolizumab (Keytruda), and nivolumab (Opdivo).
The decade ahead represents an even larger opportunity. Over the next ten years, 118 biologics are expected to lose patent exclusivity, presenting a projected $234 billion savings opportunity. However, 90% of those biologics currently have zero biosimilar in development, representing a pipeline gap that will shape which markets mature and which remain brand dominated.
The Oncology Market Is Moving Faster Than Most Pharmacists Realize
The oncology biosimilar data is particularly striking because oncology biologics represent some of the highest-cost drugs in any pharmacy panel.
Oncology biosimilars achieved an average market share of 81% within five years of launch. Trastuzumab biosimilars saw a 76% drop in average sales price within three years of competition, demonstrating that when biosimilar markets mature, price compression is dramatic and fast.
According to Craig Cowman, president of Biopharma Solutions and Strategic Sourcing at Cardinal Health: “Biosimilars are projected to continue delivering billions of dollars in savings to the healthcare industry.”
Pembrolizumab (Keytruda) generated over $25 billion in global revenue in 2024. Nivolumab (Opdivo) generated over $9 billion. Biosimilar competition for both is now entering the pipeline. When those markets open, the pharmacist who understands the substitution landscape will be the most valuable person in the room, not the last to know.
The Regulatory Environment Just Shifted in the Pharmacist’s Favor
The rules governing biosimilar substitution have been evolving rapidly, and the direction consistently favors expanded pharmacist authority.
In November 2025, the FDA announced a policy to eliminate routine switching and comparative efficacy studies for biosimilar approval, relying instead on advanced analytical technologies. This reduces development costs by up to $100 million per molecule and accelerates the speed at which biosimilars come to market.
In 2024, FDA guidance made interchangeability more accessible by reducing reliance on formal switching trials and emphasizing analytical data. In October 2025, the FDA released additional draft guidance allowing biosimilar sponsors to consider a streamlined approach to demonstrating biosimilarity, potentially without a clinical comparative study in humans.
At the press conference announcing the draft guidance, policymakers repeatedly emphasized that all biosimilars should be considered interchangeable with their reference products, and encouraged state governors to actively promote biosimilar use, framing interchangeability as a key tool to expand access and reduce costs.
The substitution landscape at the state level remains variable. As of 2026, 34 states still require prescriber approval before substitution, while 16 states allow pharmacists to switch automatically. The FDA supports automatic substitution but cannot override state law. Knowing your state’s specific requirements is not optional. It is the foundation of any biosimilar substitution program.
What Pharmacist-Led Programs Actually Achieve Real Numbers
The clearest evidence that pharmacists lead this transition better than any other model comes from the American Oncology Network’s (AON) pharmacist-driven biosimilar substitution program.
A team from AON reported real-world findings from a network-based program across 17 states in which regional clinical pharmacists facilitated biosimilar substitution opportunities between physicians and payers. The program was implemented across 107 oncologists at 76 locations.
After one year of the program, more than 90% of bevacizumab, trastuzumab, rituximab, and filgrastim orders were for the institution-preferred biosimilar product. Prior to the program, use of preferred pegfilgrastim was less than 20%. By December 2022 it had risen above 60%. Significant cost savings were documented for providers, payers, and patients.
The program’s model positions the regional clinical pharmacist as an intermediary between the pharmacy, healthcare providers, administrators, and financial teams at each practice. Using the EHR system, pharmacists send switch requests directly to the provider, who can approve within the system. The pharmacist creates a pipeline that neither the physician nor the payer could manage alone.
One investigator from a parallel pharmacy-driven biosimilar substitution study at a major oncology network put it plainly: “If you wait for the physician to do it, it isn’t going to happen.”
That observation captures everything. Biosimilar transitions don’t happen organically. They happen because a pharmacist builds the system that makes them happen.
The Barriers That Still Exist and How to Navigate Them
The AON program also documented the real-world friction pharmacists will face. Barriers to switching to institution-preferred biosimilars included nonmedical switching requirements by payers, patient assistance and compassionate use programs tied to the reference biologic, and patient or provider preference for the original product.
For pharmacists to freely substitute FDA-approved biosimilars, payers and their PBMs need to adjust reimbursement policies to be agnostic to which version of a biologic drug patients receive. Misaligned incentives and PBM rebate arrangements that favor reference biologics continue to slow adoption despite the regulatory and clinical case for substitution.
These barriers are real but navigable. The pharmacist who documents substitution outcomes, tracks payer responses, and builds a structured prescriber communication workflow transforms a complicated process into a repeatable one. That repeatability is where revenue lives.
Your 30-Minute Biosimilar Audit This Week
Pull your top 10 biologic prescriptions dispensed last month. For each one, work through three questions:
Does an FDA-approved biosimilar exist? The FDA’s Purple Book (purple.fda.gov) lists every approved biosimilar alongside its reference product and interchangeability status. It takes under two minutes per drug.
Does your state permit pharmacist substitution, and under what conditions? Interchangeability designation plus state substitution authority determines whether you can act without contacting the prescriber. Know this before you call anyone.
What does your current formulary or payer say about substitution? Some payers now actively prefer biosimilars and will reimburse at a higher rate for the substituted product. Others still favor the reference biologic due to rebate arrangements. Knowing which is which in your specific payer mix is the difference between a profitable substitution program and a frustrated one.
That 30-minute audit will map exactly where your biosimilar substitution opportunity lives. It will also show you which prescribers to contact first, the ones whose patients are currently receiving reference biologics where a preferred biosimilar exists, costs less, and your state permits substitution.
The Bigger Picture
Generics and biosimilars together represent 90% of all prescriptions filled in the United States but only 12% of total prescription drug spending. Brand medicines, at 10% of prescriptions, account for 88% of spending. In 2024, Americans spent $98 billion on generic medicines and $700 billion on brand drugs.
Every one of those $700 billion in brand drug dollars spent on a molecule that has a biosimilar equivalent represents a missed substitution. And the pharmacist, the professional who touches every one of those prescriptions at the point of dispensing, is the most structurally positioned person in the healthcare system to close that gap.
The savings are documented. The regulatory environment is shifting in your direction. The real-world programs have proven the model works. The oncology pipeline coming off patent in the next two years will create substitution opportunities for the most expensive biologics ever approved.
The pharmacists who understand this market, build a structured substitution workflow, and position themselves as the expert resource for their prescribers and payers will capture that revenue. The ones who wait for the system to route it to them automatically will watch it go elsewhere.
Sources: Association for Accessible Medicines / Biosimilars Council (2025 U.S. Generic & Biosimilar Medicines Savings Report, September 2025), Center for Biosimilars (Biosimilars Drive Savings and Access, September 2025), Cardinal Health 2026 Biosimilars Report / Managed Healthcare Executive (Physician Practices and Stable Reimbursement, March 2026), HCPLive / OncLive / AJMC (American Oncology Network Pharmacist Biosimilar Substitution Program Results), JHOP (Biosimilar Uptake and Cost-Savings Analysis, AON Program), FDA Purple Book (Biosimilar and Interchangeable Products, 2026), Paragon Institute (Platinum-Standard Science: FDA Streamlined Framework, December 2025), DIA Global Forum (Unlocking Biosimilars: Regulatory Paths to Wider Access, January 2026), AJMC (Biosimilar Interchangeability and Substitution in the US, January 2026), AMCP Journal (Real-World Familiarity with Biosimilar Regulatory Guidelines, 2025)