What are biosimilar medicines?

Page last updated: 14 November 2017

Graphic showing that biosimilar and biological medicines both come from living cells. They are very similar, but have identical effects as medicines.

Biological medicines contain substances that are made by living cells or organisms.

They are usually made of proteins that are naturally produced in the human body. When a biological medicine is given to a patient, it functions like the natural protein, resolving symptoms and preventing or slowing the progression of the disease.

Biological medicines are often administered by an injection at home or an infusion in a hospital or clinic.

A biosimilar medicine is a highly similar version of a reference biological medicine. The reference biological medicine is the first brand to market.

Biosimilar medicines can be used to treat the same diseases, in the same way, as the reference biological medicines. Biosimilar medicines are marketed once the patent on the reference biological medicine has expired.

Biological medicines, including biosimilar medicines, are used to treat serious diseases such as:

  • rheumatoid arthritis
  • inflammatory bowel diseases such as ulcerative colitis and Crohn’s disease
  • cancer
  • diabetes
  • multiple sclerosis
  • kidney disease
  • severe psoriasis

Biological and biosimilar medicines include:

  • certain hormones for hormone deficiencies (e.g. insulin for diabetes and growth hormone for growth hormone disorders)
  • monoclonal antibodies to treat autoimmune diseases and cancers
  • blood products (e.g. to treat haemophilia)
  • medicines for regulating the immune system (e.g.  to treat multiple sclerosis)
  • enzymes (e.g. to remove blood clots)
  • vaccines to prevent a number of diseases.

Biosimilar medicines currently listed on the Pharmaceutical Benefits Scheme (PBS) and approved by the Therapeutic Goods Administration (TGA) are available at 'Which biosimilar medicines are available in Australia?'.

Yes. Chemical medicines are the medicines you are probably more familiar with, which are usually available as pills or tablets. The table below shows the main differences between chemical medicines and biological (including biosimilar) medicines.

Differences between chemical medicines and biological and biosimilar medicines
Chemical medicines Biological and biosimilar medicines
Molecular structure Small, simple structure

For example, the average size of an aspirin molecule is 21 atoms:

Asprin molocule diagram

Medium to very large, complex structure

For example, the average size of a human growth hormone is around 3000 atoms:

Insulin molecule diagram

The average size of an antibody is more than 20,000 atoms:

Antibody molecule diagram

Manufacture Produced by a simple chemical process using chemical compounds Produced by a biological process using living cells or organisms
Copying All batches are exactly the same Batches may be slightly different
Availability Usually prescribed by general practitioners or specialists or can be bought over the counter Usually prescribed by specialists
Taken Usually swallowed in tablet or capsule form Usually administered by injection or infusion

Yes. The key difference is:

  • a generic medicine has exactly the same active ingredients as the original chemical medicine
  • a biosimilar medicine is highly similar to the reference biological medicine.

Biological medicines, including biosimilar medicines, are made using genetically modified cells. The genes are changed in the cell to produce the active ingredients for the medicine.

The process requires a high level of technical skill. Biological medicines, including biosimilar medicines, are carefully tested and monitored to ensure the safety, effectiveness and quality of the final medicine.

There may be small differences in the way that biological and biosimilar medicines are made. This is because the process for making the reference biological medicine is not shared with other manufacturers.

Biological and biosimilar medicines must both comply with the same quality requirements, including demonstrating that the production process can consistently produce a high-quality product.

Biosimilar medicines are specifically designed to be as similar as possible to the reference biological medicine.
There are minor differences because:

  • the cells and biological processes used to manufacture any biological or biosimilar medicine are always variable
  • the structure of the molecules is very complex, which makes them hard to fully describe
  • the biosimilar manufacturing process may not exactly match the original process.

These minor differences do not affect the safety, effectiveness or quality of the biosimilar medicine.

In fact, there are already minor differences between batches of the reference biological medicine. No two batches of a biological medicine (even from the same manufacturer) are ever exactly the same.

Biosimilar medicines are developed to make sure they are highly similar to the reference biological medicine.

This graphic illustrates the 5 basic steps for developing biosimilar medicines. 1) Define the structure and function of the reference biological medicine. 2) Create a process to make the biosimilar medicine. 3) Produce the medicine, and compare it to the reference medicine. This involves analytical, laboratory and clinical tests. 4) Submit the data to the Therapeutic Goods Administration (TGA) for review. A plan for monitoring safety and effectiveness of the medicine must also be developed. 5) The TGA assesses the data and plans to determine if the biosimilar medicine can be used.

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