Biosimilar medicines

A biosimilar is a highly similar copy of an existing drug. Speak to your doctor, nurse or pharmacist if you have any questions about your treatment.

How are drugs made?

To understand what a biosimilar is, it helps to know a bit more about how drugs are made. Drugs are divided into 2 groups:

• those made from chemical ingredients

• those made using living cells

Many drugs have specific chemical ingredients. These are non biological drugs. An example is the painkiller ibuprofen.

Other drugs are made using living cells such as those from bacteria, plants or animals. These are called biological drugs. Examples include hormones such as insulin, drugs for arthritis and some cancer drugs.

Why do we have biosimilars?

All new drugs undergo strict testing for years before they have a licence for general use.

Drug companies usually patent the new drugs they develop. This means only they can manufacture and sell the drugs for a specific time. In the UK, a patent lasts about 20 years. After this time, other drug companies can make the drug, often at a cheaper price.   

Copies of a non biological drug use the exact same chemicals. The exact copy is called a generic medicine. For example, ibuprofen was originally called Nurofen. Since this drug came off patent, various identical generic versions have been available. 

It’s not possible to copy biological medicines exactly. When the patent for a biological medicine expires, drug companies can make a drug that is like the original but not exactly the same. These drugs are called biosimilars. A biosimilar is a highly similar copy of an existing biological drug.

As with all new drugs, biosimilars are tested and have a licence for use.

The benefits of biosimilars

Biosimilar medicines are quite complicated. They are expensive to make but still cheaper than the original biological medicine. The NHS is encouraging healthcare professionals to use more biosimilars as they become available. 

Using more biosimilars should reduce cancer treatment costs in hospital trusts. It means that the drugs are available to more people who need them. Any savings can be reinvested in healthcare.

Are biosimilars safe and effective?

Biosimilars are as safe and effective as the original biological drug. Biosimilars undergo strict testing to check they work as well as the original drug. The NHS has safely used biosimilars for several years.

How are they checked?

The organisations who licence drugs: 

• check there are no differences in the way they work

• look at all information from trials used for both the original drug and the biosimilar and compare the results

• can request new studies if needed

• check and review all biosimilars in use

Are the side effects the same?

You should not experience different side effects if you have a biosimilar. As with all medicines, there is a chance that you may have a new side effect. You must tell your healthcare team if you have any side effects.

Will your doctor change you from a biologic medicine to a biosimilar during your treatment?

Your doctor might discuss this possibility with you. Remember, biosimilars are like the original drug. They have been tested to make sure they work in the same way. 

Your doctor or pharmacist can answer any specific questions you have. They will give you written information about the new drug.

Examples of biosimilars in the NHS

An example of a biological medicine is trastuzumab (Herceptin). This is a targeted cancer drug. It is used to treat breast cancer and advanced stomach cancer. Examples of biosimilars for this drug include Herzuma and Ontruzant.

Rituximab (Mabthera) is another biological medicine. It is a targeted drug. It is used to treat:

• chronic lymphocytic leukaemia

• some types of non-Hodgkin lymphoma

• some non cancer related illnesses

Biosimilars of this drug include Truxima, Ruxience and Rixathon.

Biosimilars are also used to treat other medical conditions. For example, adalimumab (Humira) treats conditions including:

• arthritis

• Crohn's disease

• ulcerative colitis

Biosimilars for this drug include Imraldi, Amgevita, Hyrimoz, Idacio, and Yuflyma.

Go to cancer drugs A-Z list