When a patient walks into your clinic with a prescription for a biologic like Humira or Enbrel, and you’re told the pharmacy can fill it with a biosimilar instead, do you know exactly what that means? If you’re like many U.S. providers, the answer might be no. Despite biosimilars being available for nearly a decade and saving billions in healthcare costs, provider education around these drugs remains inconsistent-and that’s putting patients at risk of confusion, delayed treatment, or even unnecessary fear.
What Exactly Is a Biosimilar?
A biosimilar isn’t a generic. That’s the first thing every provider needs to internalize. Generics are chemically identical copies of small-molecule drugs like metformin or lisinopril. Biosimilars, on the other hand, are complex biological products made from living cells-like antibodies, hormones, or fusion proteins. They’re not exact copies because biology doesn’t allow for perfect replication. But they don’t need to be.
The FDA requires biosimilars to show no clinically meaningful difference from their reference product in terms of safety, purity, and potency. That means the same dosing, same route of administration, same effectiveness, and same risk profile. Minor differences in inactive ingredients are allowed, but they can’t affect how the drug works in the body. For example, a biosimilar to adalimumab (Humira) must work just as well for rheumatoid arthritis, psoriasis, and Crohn’s disease-not just one of them.
Think of it like this: two different brands of insulin glargine might have slightly different preservatives or packaging, but they both lower blood sugar the same way. That’s biosimilarity. It’s not about being identical-it’s about being functionally equivalent.
Biosimilars vs Generics: The Key Differences
Here’s where confusion starts. Many providers assume biosimilars follow the same approval path as generics. They don’t. Here’s the breakdown:
- Generics: Must prove bioequivalence through one small study in healthy volunteers. No clinical trials needed for new indications.
- Biosimilars: Require extensive analytical testing, animal studies, and at least one clinical trial in humans-often involving hundreds of patients. The goal is to prove similarity across multiple dimensions: structure, function, immunogenicity, pharmacokinetics, and clinical outcomes.
And then there’s interchangeability. Not all biosimilars are interchangeable. Only those that have passed additional FDA testing-demonstrating that switching back and forth between the reference product and the biosimilar multiple times doesn’t increase safety risks or reduce effectiveness-are labeled as interchangeable. As of 2025, only about 10 of the 46 approved U.S. biosimilars have this designation. That’s critical because only interchangeable biosimilars can be substituted at the pharmacy without prescriber involvement, depending on state law.
Yet, a 2021 survey found that 63% of U.S. physicians couldn’t correctly identify this distinction. That’s not just a knowledge gap-it’s a patient safety risk.
Why Provider Education Is Lagging
It’s not for lack of resources. The FDA has published a free, comprehensive Teaching Resource Guide with 12 modules covering everything from manufacturing to immunogenicity. They’ve trained 147 medical schools, 134 pharmacy schools, and over 200 nursing programs. Yet, only 38% of U.S. physicians describe themselves as “extremely familiar” with the FDA’s definition of biosimilarity.
Why? Because education isn’t happening where it matters most: at the point of care. Most providers learned about drugs in school a decade ago, and biosimilars weren’t on the radar then. Now, they’re being introduced in fast-moving, high-stakes environments-oncology clinics, rheumatology practices, endocrinology offices-without structured training.
Studies show a clear link between education and confidence. In a 2017 study of oncology staff, providers who went through 12 training sessions over four months went from 40.1% confidence in biosimilar efficacy to 92%. That’s not a small jump-it’s transformative.
Meanwhile, younger providers-those under 40-are 40% less familiar with biosimilars than their more experienced colleagues. That’s alarming. If new doctors aren’t being trained properly now, the knowledge gap will widen.
Who’s Leading in Adoption? Who’s Falling Behind?
Adoption isn’t uniform. Rheumatologists are ahead of the curve-68% use biosimilars regularly. Oncologists aren’t far behind at 52%. But endocrinologists? Only 29%. And yet, insulin biosimilars have been available since 2015.
Why the gap? It comes down to three things: familiarity, fear, and workflow.
- Familiarity: Rheumatologists and oncologists have been exposed to biosimilars longer. They’ve seen data from Europe, where biosimilars have been used for over a decade with strong safety records.
- Fear: Endocrinologists worry about switching insulin-especially in elderly or diabetic patients with complex regimens. They fear hypoglycemia or loss of glycemic control. But real-world data from Sweden and Germany show no increased risk.
- Workflow: Many EHR systems don’t distinguish between biosimilars and reference products. In 78% of U.S. hospitals, providers report difficulties documenting biosimilar use. If your system just says “adalimumab,” you can’t track whether the patient got Humira or a biosimilar. That breaks pharmacovigilance and makes it harder to report adverse events.
At UCSF Medical Center, pharmacist-led education cut prescribing hesitancy from 58% to 12% in six months. How? They didn’t just hand out pamphlets. They held monthly case reviews, created quick-reference cards for common biosimilars, and integrated biosimilar tracking into the EHR. Simple, targeted, and practical.
Interchangeability and State Laws: What You Need to Know
Even if a biosimilar is FDA-approved as interchangeable, that doesn’t mean it can be automatically substituted. That decision rests with state law. As of 2025, 42 states have passed substitution laws-but they vary wildly.
- 12 states require immediate prescriber notification when substitution occurs.
- 24 states allow substitution with a 7-day notice to the prescriber.
- 6 states have no notification requirement at all.
And here’s the kicker: only interchangeable biosimilars can be substituted at the pharmacy without a new prescription. If a patient walks in with a prescription for “adalimumab,” and the pharmacy dispenses an interchangeable biosimilar, they can do it without calling you. But if it’s a non-interchangeable biosimilar? They must contact you first.
That means you need to know: Is this biosimilar interchangeable? Does my state require notification? Does my patient’s insurance cover it? If you don’t know the answer to those questions, you’re flying blind.
Immunogenicity: The Biggest Misconception
One of the most persistent myths is that biosimilars cause more immune reactions than the original biologic. That’s not true.
The FDA requires manufacturers to demonstrate that the immunogenicity profile of a biosimilar is comparable to the reference product. That means similar rates of anti-drug antibodies, similar rates of infusion reactions, and similar rates of loss of response over time.
Studies tracking patients for up to five years show no difference in immune-related adverse events between biosimilars and originators. In fact, the European experience shows lower rates of immunogenicity with biosimilars in some cases-likely because they’re manufactured under stricter quality controls in newer facilities.
Still, 57% of U.S. providers express concern about using biosimilars for indications not directly studied in clinical trials. That’s called “extrapolation.” And it’s not just allowed-it’s standard practice. If a biosimilar works in rheumatoid arthritis and the manufacturer can show it’s highly similar to the reference product, the FDA can approve it for psoriasis, Crohn’s, or ankylosing spondylitis-even if no clinical trial was done in those conditions. Why? Because the mechanism of action is the same. The same logic applies to generics: if you prove bioequivalence for hypertension, you don’t need separate trials for heart failure.
How to Get Educated (And What to Do Today)
You don’t need a six-month course. Start here:
- Go to the FDA’s Biosimilar Education Page. Download their Teaching Resource Guide. It’s free, peer-reviewed, and updated annually. Spend 90 minutes on Modules 1, 4, and 7.
- Ask your pharmacy. When a biosimilar is dispensed, ask: Is it interchangeable? Is it approved for this indication? What’s the product name?
- Update your EHR. Work with your IT team to create a dropdown for biosimilars in your prescribing system. Don’t let them all roll into one generic “adalimumab” field.
- Talk to your patients. Don’t assume they know what a biosimilar is. Use simple language: “This is a highly similar version of the drug you’ve been taking. It’s been tested just as rigorously and works the same way.”
- Join a local learning group. Many hospitals now have pharmacist-led biosimilar education sessions. Attend one. Bring your team.
The savings are real. Medicare Part B biosimilars cost 28% less than reference products. Over the next decade, biosimilars could save the U.S. healthcare system $150 billion. But none of that matters if providers don’t understand how to use them.
What’s Next?
By 2025, the Association of American Medical Colleges plans to integrate biosimilar education into 95% of medical school curricula. That’s progress. But we can’t wait for the next generation. We need to educate the providers who are prescribing today.
Every time you choose a biosimilar over a reference product, you’re not just saving money-you’re making a life-saving therapy more accessible. But that only works if you know what you’re prescribing.
Start small. Learn one biosimilar this week. Talk to one patient about it. Update one EHR field. That’s how change happens.
Are biosimilars the same as generic drugs?
No. Generics are chemically identical copies of small-molecule drugs and only need to prove bioequivalence in one study. Biosimilars are complex biological products made from living cells. They require extensive analytical testing, animal studies, and at least one clinical trial to prove they are highly similar to the reference product with no clinically meaningful differences in safety or effectiveness.
Can biosimilars be automatically substituted at the pharmacy?
Only if they’re designated as “interchangeable” by the FDA and your state allows substitution. Not all biosimilars are interchangeable. Only about 10 of the 46 approved in the U.S. have this status. Even then, state laws vary-some require prescriber notification, others don’t. Always check your state’s rules and the product label.
Do biosimilars cause more immune reactions than the original biologic?
No. The FDA requires biosimilars to demonstrate comparable immunogenicity profiles to the reference product. Real-world data from Europe and the U.S. show no increased risk of anti-drug antibodies, infusion reactions, or loss of response. In some cases, newer manufacturing processes for biosimilars may even reduce immunogenicity.
Why are some doctors hesitant to use biosimilars?
Common concerns include fear of reduced effectiveness, uncertainty about extrapolation (using a biosimilar for indications not directly studied), and EHR documentation challenges. Many providers weren’t trained on biosimilars during medical school. Studies show that after targeted education, provider confidence in biosimilars increases from under 40% to over 90%.
What’s the biggest barrier to biosimilar adoption?
The biggest barrier is lack of provider education-not cost or safety. While biosimilars are proven safe and cost 15-30% less, 63% of U.S. physicians can’t correctly explain how they differ from generics. EHR systems that don’t track biosimilars separately and inconsistent state substitution laws also contribute, but education is the foundation for all other progress.
How can I start using biosimilars confidently?
Begin by reviewing the FDA’s free Teaching Resource Guide. Focus on Modules 1 (What is a biosimilar?), 4 (Interchangeability), and 7 (Clinical Evidence). Talk to your pharmacy team about which biosimilars are available and whether they’re interchangeable. Update your EHR to distinguish biosimilars from reference products. Start with one drug class-like TNF inhibitors-and build from there. Educate your patients using simple, clear language.
