Tumour necrosis factor (TNF) inhibitors

TNF inhibitors are medicines that help stop inflammation. They're used to treat diseases like rheumatoid arthritis (RA), juvenile arthritis, psoriatic arthritis, plaque psoriasis, ankylosing spondylitis, ulcerative colitis (UC), and Crohn's disease.

On this page you will find information about:

Examples of TNF inhibitors
What are TNF inhibitors?
Subsidy restrictions
How are TNF inhibitors given?
Monitoring and investigations
Side effects

Examples of TNF inhibitors

Examples of TNF inhibitors available in New Zealand include:

adalimumab (Humira®)
etanercept (Enbrel®)
infliximab (Remicade®).

What are TNF inhibitors?

TNF inhibitors are used to treat certain types of autoimmune conditions. These are conditions in which your body's defence system (immune system) attacks healthy tissues. They include conditions such as:

rheumatoid arthritis and psoriatic arthritis
bowel conditions such as Crohn's disease, ulcerative colitis
skin conditions such as chronic plaque psoriasis.

TNF inhibitors work by blocking natural inflammatory substances in your body called tumor necrosis factor alpha. This helps to decrease swelling (inflammation) and weakens your immune system, thereby slowing or stopping damage from the condition.

Watch videos about the use of adalimumab, etanercept and infliximab for the treatment of arthritis.

Subsidy restrictions

TNF inhibitors are expensive medicines with a potential for serious side effects. They are used in selected people when standard treatments have been unsuccessful. In New Zealand, TNF inhibitors are funded with restrictions (PHARMAC subsidy restrictions). To qualify for subsidy, the initial application for treatment must come from an appropriate named specialist, eg, a rheumatologist, gastroenterologist or dermatologist.

How are TNF inhibitors given?

TNF inhibitors are given by injection.

Adalimumab and etanercept are given by subcutaneous injection (into your skin), usually in your thigh or abdomen (tummy area). Change the site for each injection. Do not inject in an area that is bruised, red, hard or tender.
Infliximab is given by intravenous infusion (as a drip) into a vein.

Monitoring and investigations

TNF inhibitors have the potential for serious side effects, including an increased risk of infection.

Before prescribing a TNF inhibitor, your doctor will test for infections such as tuberculosis (TB), hepatitis and chickenpox.
To monitor the safety of TNF inhibitors and how well they are working, your doctor will order blood tests before you start treatment and regularly while you are on it. Common tests used are full blood count, liver function test and C-reactive protein test.

Vaccinations

Before starting on a TNF inhibitor, your doctor will review your immunisation record to make you have received all vaccinations recommended on the New Zealand Immunisation Schedule. You may need to catch-up if you have missed any vaccinations.

Live vaccinations, such as varicella (chickenpox) vaccine, tuberculosis (BCG) and measles, mumps rubella (MMR), must be avoided if you are receiving treatment with a TNF inhibitor. They should be completed before starting treatment.
The following vaccines are safe to take while receiving treatment with a TNF inhibitor:

Side effects

Like all medicines, TNF inhibitors can cause side effects although not everyone gets them.

Side effects	What should I do?
Reaction at the injection site such as bruising, redness, tenderness.	Change the site for each subcutaneous injection. Tell your doctor or phone Healthline 0800 611 116.
Increased risk of infections – because TNF inhibitors weaken your body's immune system, they have been associated with increased risk of infections. These infections may be mild (such as colds or sinusitis) or more severe such as tuberculosis (TB) and septicaemia (infection of your blood).	Contact your doctor immediately if you develop signs of infection such as fever (high temperature), an ongoing cough, weight loss, sore throat or feeling weak, tired and unwell.
Signs of an allergic reaction such as muscle or joint pain, fever, rash, intense itching, swelling of your face or hands, sore throat, headache or difficulty swallowing.	Tell your doctor immediately or phone Healthline 0800 611 116.