Biosimilars: What You Should Know

These safe and effective drugs are highly similar to biologics and may be less expensive.

A new generation of arthritis drugs called biosimilars entered the U.S. market in 2016. These Food and Drug Administration (FDA)-approved medications are  copycat versions of familiar biologic medications used to treat rheumatoid arthritis (RA), psoriatic arthritis (PsA), ankylosing spondylitis, juvenile idiopathic arthritis, lupus and other conditions, including psoriasis and inflammatory bowel disease. Biosimilars are safe and effective treatment options. The FDA requires that they meet rigorous approval standards.

Although many biosimilars have been approved to treat inflammatory arthritis, far fewer are available for doctors to prescribe. The others are stalled by legal delays. Click here for the latest list of FDA approvals.

Comparing Biosimilars and Biologics

A biosimilar is a biologic. According to the FDA, biosimilars:

  • Are made with the same types of natural sources.
  • Are given the same way.
  • Provide the same treatment benefits.
  • Have the same potential side effects.
  • Have the same strength and dosage.

“Biosimilars have the same amino acid sequence as biologics, [the same] potency, dosing, route of administration and clinical effects. The ways in which they differ aren’t significant,” explains Jonathan Kay, MD, director of clinical research in rheumatology at University of Massachusetts Memorial Medical Center in Worcester.

Once a drug has been shown to be biosimilar to a reference product, it can be approved for all the same conditions (or “indications”) as that reference product even if it hasn’t been specifically tested for each and every condition, thanks to a concept called “extrapolation.”

“Biosimilar” is not the same as “generic.” Generics are exact copies of chemically synthesized medicines. Biosimilars are made in natural and living cells. They are highly similar but not exact copies of original biologics (also called reference products). It’s impossible to perfectly replicate original biologics because they are very large and complex molecules. However, biosimilars are made from the same types of living sources as original biologics. Before approving them, the FDA makes sure that biosimilars are as safe and effective as the original biologic and work in the same way.

Biosimilars might cost less. Biologics are expensive. They can cost a patient several thousands of dollars out of pocket each month, depending on the patient’s insurance plan. Biosimilars are predicted to cost less – although ultimately how much less (and whether consumers will see any savings) is based on insurance plans. Competition from biosimilars may drive down the price of branded biologics, too, though that’s not a given. Manufacturers are providing co-pay cards, and discount coupons are available from online retailers like

The “Substitution” Issue

According to the FDA, “An interchangeable product is a biosimilar product that t is expected to produce the same clinical result as the reference product in any given patient.”

The concern for many patients and doctors is that “interchangeability” opens the door for the pharmacist to substitute a biosimilar for the branded biologic without consulting the prescribing physician or making a patient aware of the substitution. Many states have passed or are considering laws governing substitutions, although some doctors would prefer to see a more uniform, nationwide approach.

The Arthritis Foundation, which has been instrumental in getting the legislation passed in states, maintains that doctors and patients need to be informed in a timely manner if a substitution occurs, and that doctor should be able to override a substitution in certain cases.

In 2023, a number of biosimilars to Humira (adalimumab) became available, including the first interchangeable biosimilar, Cyltezo, for inflammatory forms of arthritis, psoriasis and inflammatory bowel disease. These are the first self-injectable biosimilars on the market for rheumatic conditions, and while all of them are the drug adalimumab, each is sold under a different name. 

To determine if a biosimilar is right for you, the first step is to check if it’s included on your drug formulary. Then talk to your doctor about the pros and cons of switching and any concerns you have. 

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