What is infliximab?
Infliximab belongs to the class of biological response modifiers called tumour necrosis factor (TNF) blockers. The trade name for the original drug is Remicade®. Generic infliximab biosimilars are also marketed or are under development (including Remsima™, Inflectra™, Infliximab BS "NK").
What is infliximab used for?
Infliximab is currently approved in adults and children over the age of 6 years for the treatment of psoriasis and psoriatic arthritis, as well as rheumatoid arthritis, ankylosing spondylitis, Crohn disease and ulcerative colitis.
In one major study, infliximab very quickly and effectively controlled psoriasis and in about half of the patients, the disease stopped progressing further after just three doses of the medicine.
How does infliximab work?
Infliximab is biologically engineered from human and mouse antibody molecules. It works by directly binding to tumour necrosis factor (TNF) in the blood and diseased tissue. Infliximab-bound TNF cannot bind to or activate TNF receptors, which are involved in the development of psoriatic plaques.
How is infliximab given?
Infliximab is administered by intravenous infusion over 2 hours in a specialist centre. Patients receiving infliximab require close supervision and monitoring throughout treatment. It is repeated after 2 and 6 weeks. If effective, treatment may be repeated every 8 weeks.
Patients on infliximab are often also prescribed methotrexate, which helps to prevent the formation of anti-infliximab antibodies.
Contraindications to infliximab
Infliximab should not be used under the following circumstances.
- Untreated chronic infection, such as tuberculosis or viral hepatitis B or C
- Patients with moderate to severe congestive heart failure
- Known hypersensitivity to murine proteins or any other component of the product
Precautions while on infliximab
Caution must be taken when considering the use of infliximab in patients prone to infections or in those with chronic or recurrent infections.
- Patients should be tested for tuberculosis (TB), viral hepatitis B/C and human immunodeficiency virus (HIV) before starting infliximab.
- Treatment should be stopped if a serious infection occurs, for example requiring hospitalisation or intravenous antibiotics. It can often be recommenced once the infection has been effectively treated.
- Uncommon infections with organisms such as listeria and legionella may be more common and more serious in patients on infliximab.
Infliximab should also be used with caution in the following situations:
- Mild congestive heart failure
- Pre-existing central nervous system (CNS) disorders, e.g. seizures
- Elderly patients
- Patients with kidney or liver failure
- During pregnancy and breastfeeding
Patients who require major surgery may be advised to stop infliximab temporarily about 4 weeks prior to a planned operation. It can be started again 2 weeks after surgery providing no infection is present.
Vaccinations and infliximab
Immunisation status should be reviewed prior to starting infliximab. If necessary, vaccines should be updated prior to treatment. Annual influenza vaccination is recommended.
As they may induce illness in immunodeficient individuals, live vaccines should not be used during treatment with infliximab. Currently, available live attenuated viral vaccines include measles, mumps, rubella, varicella, yellow fever, influenza (intranasal vaccine) and the oral polio vaccine. Live attenuated bacterial vaccines include BCG and oral typhoid vaccine.
What are the side effects of infliximab?
Infliximab is well tolerated in most people. If any of the following symptoms are severe or do not go away you should contact your doctor.
- Nausea and/or vomiting
- Stomach pain
- Fever and night sweats
- Fatigue and muscle weakness
- Unexpected weight loss
Acute infusion-related reactions include difficulty in breathing or swallowing, chest pain, swelling of face, lips, or hands, dizziness and headache, flushing, urticaria, and burning at the IV infusion site. These may be treated by reducing the rate of infusion and with paracetamol and antihistamines.
In a small number of patients, lupus-like symptoms and signs may occur. These include photosensitivity and joint and muscle pain (arthritis and arthralgias). Treatment should be stopped if these occur.
Severe cutaneous reactions have rarely been reported, including Stevens-Johnson syndrome and toxic epidermal necrolysis. Some patients have been reported to develop drug-induced vitiligo, dermatitis, chronic plaque psoriasis, and palmoplantar pustulosis.
Like all medications that work on the immune system, infliximab may increase the risk of certain types of lymphoma. These have rarely been reported in patients on infliximab, usually in those also taking other medicines that suppress the immune system such as azathioprine or mercaptopurine. Skin cancers, in particular squamous cell carcinoma, have also been reported in patients on infliximab. These patients usually have other risk factors such as severe sun damage or previous treatment with photochemotherapy (PUVA).
Monitoring while on infliximab
Regular follow-up visits to monitor the safety and efficacy of treatment are necessary. It is recommended that patients on biologic medications have routine blood tests every 6 months or so, including full blood count and liver function tests. TB tests should be repeated from time to time.
We suggest you refer to your national drug approval agency such as the Australian Therapeutic Goods Administration (TGA), US Food and Drug Administration (FDA), UK Medicines and Healthcare products regulatory agency (MHRA) / emc, and NZ Medsafe, or a national or state-approved formulary eg, the New Zealand Formulary (NZF) and New Zealand Formulary for Children (NZFC) and the British National Formulary (BNF) and British National Formulary for Children (BNFC).