What are Biosimilars?

Article Featured Image Biosimlars

Get ready, biosimilars are starting to be FDA-approved, but are not to be confused with “generic” medications.

The short answer is that biosimilars are FDA-approved drugs that are comparable to FDA-approved biologic drugs. So, let’s begin by explaining biologic drugs.

What are Biologics?

Biologic drugs work by interrupting the immune system to help your body fight a disease. For inflammatory diseases such as rheumatoid arthritis (RA). The inflammatory destruction of RA can damage many body systems—the skin, eyes, lung, heart, and blood vessels.  

Biologic drugs target specific released chemicals that play roles in the inflammatory process. The biologic drugs attack the overproduction of immune system cells that are destroying healthy cells and causing the destructive RA inflammatory systems.

There is also biologic therapy for cancer. The therapy has two strategies that can be used. One is to stimulate the immune system to attack cancer cells and the other is making cancer cells easier for the immune system to recognize.


Making biologic drugs requires a complex manufacturing process and are created in a living system such as a microorganism, plant, or animal cells.

A chemical drug such as aspirin or ibuprofen is manufactured by combining specific chemical ingredients in an ordered process. But biologic drugs are produced using recombinant DNA.

Biologics are large, complex proteins and producing them consists of four main steps:

  1. Producing the master cell line containing the gene that makes the desired protein
  2. Growing large numbers of cells that produce the protein
  3. Isolating and purifying the protein
  4. Preparing the biologic for use by patients

At every step in the process the environment the cells need in order to thrive must be maintained. Variables such as temperature, PH, nutrient concentration, and oxygen levels must be controlled. Frequent tests to detect any contamination from bacteria, yeast, or other microorganisms must be carried out.

When the growth process is complete and the desired protein has been isolated from the growth media, filtering technologies are used to isolate and purify the proteins based on size, molecular weight, and electrical charge. Then the purified protein is mixed with a sterile solution and put into vials or syringes with individual doses so the drug can be either injected or infused into the patient.

What are Biosimilar Drugs?

According to the FDA a biosimilar is a biological product that is approved based on data showing that it is highly similar to a biological product already approved by the FDA (reference product) and has no clinically meaningful differences in terms of safety, purity and potency (i.e., safety and effectiveness) from the reference product, in addition to meeting other criteria specified by law.

Manufacturing Biosimilars

Manufacturing a biosimilar is done by genetically modifying a cell, that modified cell becomes the cell line used for the production of the protein needed for the biologic medicine.

The protein is then separated from the cells and purified. Biosimilars are created from small alterations to the manufacturing process which creates a molecule that is not identical but closely resembles the reference product. A reference product is the single biological product already approved by the FDA.

According to the FDA, minor differences between the reference product and the proposed biosimilar product in clinically inactive components are acceptable. For example, these could include minor differences in the stabilizer or buffer compared to what is used in the reference product. Any differences between the proposed biosimilar product and the reference product are carefully evaluated by FDA to ensure the biosimilar meets FDA’s high approval standards.

Biosimilars are Cheaper

Biosimilars are often less expensive than biologic drugs because the original drug development has already been done and so the production costs are lower. Some online retailers like GoodRx may offer discount coupons for non-branded products like biosimilars, which can help lower the cost as well.

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Gregory Scimeca, M.D.
Ophthalmologist and Medical Director
The Eye Professionals

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