Examples

Generic Name	Brand Name
adalimumab	Humira
infliximab	Remicade
natalizumab	Tysabri

How It Works

A tumor necrosis factor (TNF) antagonist is a type of antibody that inhibits tumor necrosis factor, a protein that increases inflammation in the body. Infliximab, adalimumab, and natalizumab block the inflammatory response that happens in Crohn's disease and ulcerative colitis. They are given as a shot. Infliximab and natalizumab are given as a shot in a vein (intravenous, or IV) and adalimumab is given as a shot under the skin (subcutaneous).

Why It Is Used

Infliximab was first used to treat abnormal connections (fistulas) between the intestines and organs in moderate to severe Crohn's disease. Now it is used to induce and maintain remission (a period without symptoms) in people who have Crohn's disease or ulcerative colitis that has not improved with other medicines.

Adalimumab and natalizumab are used to induce and maintain remission in people with Crohn's disease who have not improved with other medicines and who no longer respond to or cannot tolerate treatment with infliximab.

How Well It Works

Infliximab can induce remission in people with moderate to severe Crohn's disease, including the closing of fistulas. In one study, some people who were treated with infliximab had symptoms that came back after 3 months. It is now recommended that people treated with infliximab continue to get the medicine at regular intervals. This is called maintenance therapy.

In multiple studies, almost 70% of people taking infliximab had fewer symptoms or had healed fistulas.¹

In one study, between 60% and 70% of people with ulcerative colitis were better 8 weeks after getting infliximab treatment. In another study, twice as many people got better after receiving infliximab compared to those taking a placebo.²

Adalimumab has shown promise in treating Crohn's disease in multiple studies.³ It works like infliximab and may be good for people who are allergic to infliximab.

Few studies have been done with natalizumab and Crohn's disease. But the studies that have been done show that natalizumab works well to treat Crohn's disease.¹

The long-term effectiveness of these medicines is still being studied.

Side Effects

The most common side effect of TNF antagonists is an allergic reaction to the injection (shot) or infusion (medicine given in a vein-intravenously, or IV). If you have a reaction to the shot or infusion, it will happen right away, either during the infusion or within 1 to 2 hours after the infusion or shot. Your doctor may give you medicines to prevent or stop the reaction.

Symptoms of a shot or infusion site reaction include:

• Fever.
• Chills.
• Chest pain.
• Shortness of breath.
• Itching (pruritus).
• Headache.
• Nausea.
• Heat and redness (flushing) in the face.
• Rash.
• Fatigue.
• Dizziness.

Warnings about serious side effects of TNF antagonists have been issued. The U.S. Food and Drug Administration (FDA) and the drug’s manufacturers have warned about:

• An increased risk of a serious infection (such as tuberculosis). If you have had tuberculosis (TB) or know someone who has had it, tell your doctor. TNF antagonists also affect your body's ability to fight all infections. So if you get a fever, cold, or the flu while you are taking one of these medicines, let your doctor know right away.
• An increased risk of blood or nervous system disorders. Call your doctor if you have symptoms of blood disorders (such as bruising or bleeding) or symptoms of nervous system problems (such as numbness, weakness, tingling, or vision problems).
• A possible increased risk of lymphoma (a type of blood cancer). It is not clear whether this increase is because of the drug or because people with this disease may already have a higher risk. There have been reports of a rare kind of lymphoma, occurring mostly in children and teens taking TNF antagonists, that often results in death.
• An increased risk of liver injuries. Call your doctor if your skin starts to look yellow, if you are very tired, or if you have a fever or dark brown urine.

In very few cases, natalizumab has caused a serious and life-threatening disease called PML. Natalizumab is tightly controlled because of this. If you take natalizumab, you will need to enroll in a program called the Crohn's Disease–Tysabri Outreach Unified Commitment to Health (CD-TOUCH) Prescribing Program.

What To Think About

TNF antagonists are more expensive than other medicines used to treat Crohn's disease.

TNF antagonists are used for Crohn's disease and ulcerative colitis that has not improved (refractory disease) when treated with corticosteroids, aminosalicylates, antibiotics, azathioprine, or 6-mercaptopurine.

The use of TNF antagonists during pregnancy is still being studied. Some of them may be used when other medicines have not worked and the health of the mother or of the fetus (or both) is at risk. It is not known if TNF antagonists can pass from the mother to the baby in breast milk. If you have inflammatory bowel disease and you are pregnant, thinking about becoming pregnant, or breast-feeding, talk to your doctor about what medicines are safe for you to use.

Because adalimumab is given as a shot under the skin, you may be able to do the shots yourself after your doctor has shown you how.

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Citations

1. Friedman S, Lichtenstein GR (2006). Crohn's disease. In MM Wolfe et al., eds., Therapy of Digestive Disorders, 2nd ed., pp. 785–801. Philadelphia: Saunders Elsevier.

2. Rutgeerts P, et al. (2005). Infliximab for induction and maintenance therapy for ulcerative colitis. New England Journal of Medicine, 353(23): 2462–2476.

3. Sandborn WJ, et al. (February 13, 2007). Adalimumab for maintenance treatment of Crohn's disease: Results of the CLASSIC II trial. Online version of Gut, available at: http://gut.bmj.com/cgi/rapidpdf/gut.2006.106781v1.