Drugs used to reduce the activity of the body’s immune system
Cytotoxic anticancer drugs
Immunosuppressants reduce the activity of the body’s immune system. The immune system protects the body against infection and helps to destroy diseased cells. However, in certain conditions, known as autoimmune disorders, the immune system acts against the body’s healthy tissues, and immunosuppressant drugs may be required to protect them from damage. Immunosuppressants are also used to prevent rejection of donor tissue and organs after transplant surgery. Some immunosuppressants are also used to treat certain cancers.
People who are taking immunosuppressant drugs are at increased risk of infection because the drugs reduce the body’s ability to fight disease.
What are the types?
There are various types of drugs that suppress the activity of the immune system. The most commonly used ones are corticosteroids, disease-modifying antirheumatic drugs, and some cytotoxic anticancer drugs.
Oral corticosteroids are widely used in the treatment of autoimmune disorders, such as systemic lupus erythematosus and rheumatoid arthritis. They are also used to prevent transplant rejection and some, such as prednisolone, are used to treat some types of cancer, such as certain leukaemias and lymphomas. They inhibit the activity of white blood cells, which are an essential component of the immune response, and also reduce inflammation.
Prolonged used of oral corticosteroids may cause acne, the development of a moon-shaped face, and weight gain. They also increase the risk of developing osteoporosis, high blood pressure (see Hypertension), and diabetes mellitus, and may make some otherwise minor infections, such as chickenpox, life-threatening. You should not stop taking oral corticosteroids suddenly. Your doctor or pharmacist will issue a card giving details of your treatment, which you should carry at all times in case of a medical emergency.
Disease-modifying antirheumatic drugs
Often known as DMARDs, these drugs are used to treat rheumatoid arthritis and certain other autoimmune disorders, such as systemic lupus erythematosus. Some of these drugs, such as ciclosporin, are also used to prevent transplant rejection, and others, such as rituxumab, are used to treat certain cancers.
DMARDs are a diverse group of drugs and affect the immune system in a variety of different ways, although in general they reduce its activity. They may cause potentially serious side effects, such as kidney, liver, blood, or eye problems, and therefore people taking them are monitored regularly.
Cytotoxic anticancer drugs
These drugs are used primarily to treat cancers such as leukaemia and lymphoma but some, such as methotrexate and cyclophosphamide, have an immunosuppressant effect and are also used to treat noncancerous autoimmune disorders such as rheumatoid arthritis. Cytotoxic immunosuppressants suppress the immune system by inhibiting the growth of new white blood cells in the bone marrow.
Cytotoxic immunosuppressants can cause side effects including nausea, vomiting, diarrhoea, hair loss, and abnormal bleeding. People taking such drugs need regular blood tests to monitor the drug’s effects.
In addition to the drugs already discussed, various other drugs also have an immunosuppressant effect. Some of these drugs are used to prevent transplant rejection, for example, antithymocyte immunoglobulin, basiliximab, and tacrolimus, which work by suppressing lymphocytes (types of white blood cells), and sirolimus, which works by inhibiting the production of antibodies (substances made by white blood cells to neutralize foreign proteins in the body). Alemtuzumab, which suppresses lymphocytes, is used to treat some cases of leukaemia. Glatiramer acetate, whose method of action is unknown, and natalizumab, which inhibits the movement of white blood cells, are used to treat multiple sclerosis.
These drugs may cause a wide range of side effects, most commonly gastrointestinal disturbances, such as nausea and vomiting, fever, and chills. They may also cause various potentially more serious side effects, such as hypersensitivity reactions, high or low blood pressure, and heart, kidney, liver, nervous system, or blood disorders. For this reason, people taking these drugs are monitored regularly.
When taking immunosuppressant drugs, it is important to report any signs of infection, such as a sore throat or fever, or any unusual bruising or bleeding to your doctor immediately. If you are taking oral corticosteroids, you should not stop them suddenly.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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