Nurse, what are biosimilars?

I paused from the other side of the infusion center when I overheard a patient ask my colleague this question. After a very long pause, I heard her response.

Nurse: Where did you hear that?

Patient: Dr. XXX said I might get the biosimilar drug when it comes out.

<long pause again>

Nurse: Oh really?  Ok, let’s get your infusion started.

<End of conversation.>

I doubt that many infusion nurses really know much about biosimilars to confidently explain to a patient what they are. Perhaps they’ve read or heard about it in the news but still a bit unsure what they are. Here’s a quick FYI..

What are biosimilars?

Biosimilars are a type of biological product that are licensed (approved) by FDA because they are highly similar to an already FDA-approved biological product, known as the biological reference product (reference product), and have been shown to have no clinically meaningful differences from the reference product.

If you recall, biological products are made from living organisms. The material they are made from can come from many sources, including humans, animals and microorganisms such as bacteria or yeast. Biological products are manufactured through biotechnology, derived from natural sources or, in some cases, produced synthetically. Biological products are among the medications used to treat conditions such as rheumatoid arthritis, anemia, low white blood cell counts, inflammatory bowel disease, skin conditions such as psoriasis and various forms of cancer.

Biosimilars need to have the same mechanism of action as the reference product it was compared to, which means it will work in the same way as the reference product. The FDA will only approve a biosimilar product if it has the same mechanism of action, route of administration, dosage form, and strength as the reference product. Additionally, a biosimilar can only be approved for the indications and conditions of use that have been previously approved for the reference product.

As of today, there are two approved biosimilars in the US:

  • Zarxio (biosimilar) – Neupogen (reference product).
  • Inflectra (biosimilar) – Remicade (reference product)

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What else should we know about biosimilars?

  • Biosimilars are not interchangeable biological products. An interchangeable biological product, in addition to meeting the biosimilarity standard, is expected to produce the same clinical result as the reference product in any given patient, and for a product that is given to a patient more than once, the risk in terms of safety and effectiveness of alternating or switching between the interchangeable and the reference product is not greater than the risk of using the reference product without alternating or switching.
  • Biosimilars are not generic versions. Generic drugs are copies of brand-name drugs, have the same active ingredient, and are the same as those brand name drugs in dosage form, safety, strength, route of administration, quality, performance characteristics and intended use. That means the brand-name and the generic are bioequivalent.  Biosimilars are highly similar to the reference product they were compared to, but have allowable differences because they are made from living organisms. Biosimilars also have no clinically meaningful differences in terms of safety, purity, and potency from the reference product.
  • Are biosimilars cheaper?  That seem to be the expectation as biosimilars enter the US market. There are only two biosimilars approved at this point, one approved a bit longer than the other. Honestly, I can’t find data on the real vs potential savings. As they say during elections – too early to call!  But one thing it will do is create greater competition in the US market.

What should infusion nurses know about administering biosimilars?

  • Take the initiative to educate yourselves about biosimilars and understand the differences in terminology.  Don’t rely on the company’s product education, which are often tailored for the prescribers. Biosimilar is not the same as  bioequivalent and not interchangeable.
  • Don’t be complacent just because you have administered the reference product before and now you’re told to administer a similar product. Don’t assume that all products used for the same condition will exhibit identical therapeutic properties with predictable adverse events and no anticipated difference from one product to another.
  • Know whether you are giving a biosimilar or a reference product. I know this is easy for now but as more biosimilars are approved, you’ll need to know which is which. There will be four lower case letters assigned by the FDA at the end of the product name. For example – Zarxio – filgrastrm-sndz  and Inflectra – infliximab-dyyb. If in doubt, always ask your pharmacist.
  • Be vigilant and report side effects, known/unknown, to better understand the effects of biosimilars on patient outcomes.

There’s much more to learn as more biosimilars are approved.


For more information about biosimilars, take the free continuing education course developed by the FDA. click here

For information on biosimilars for the consumer or to share with patients – click here


  1. Information for Healthcare Professionals (Biosimilars) FDA  –
  2. Information for Consumers (Biosimilars) FDA
  3. FDA Zarxio Press Announcement –
  4. FDA Inflectra Press Announcement –



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