Etanercept (brand name Enbrel, pronounced En-Brell) was the first treatment approved in January 2002 by the U.S. Food and Drug Administration specifically for psoriatic arthritis. Enbrel is also in development for the treatment of psoriasis.

Enbrel is also used to treat adult and juvenile rheumatoid arthritis. It has been on the market in the U.S. since 1998 and has been used in more than 100,000 patients.

How does it work?

Enbrel blocks a "messenger" in psoriatic arthritis that signals other cells to cause inflammation. Enbrel works by inhibiting tumor necrosis factor-alpha (TNF-alpha), an immune-system chemical messenger. In psoriatic arthritis and psoriasis, TNF-alpha is present in increased levels, which causes inflammation and can lead to tissue and joint damage. TNF-alpha can also lead to increased immune system activity through the activation of T cells. T cells are a type of white blood cell in the body; in psoriasis, once T cells are mistakenly activated, they can trigger inflammation and other immune responses and fuel the development of psoriasis lesions. Enbrel is similar in its actions to other TNF-alpha-blocking or -inhibiting drugs such as Remicade.

Because Enbrel is a protein, it would be digested if taken orally. It is given by subcutaneous injection two times a week. People can give themselves the injections at home.

What are the side effects of Enbrel?

• It can cause minor reactions at the site of injection. The skin may become red, warm and tender. This effect is generally mild and doesn't require one to stop treatment.
• People with known multiple sclerosis should not take Enbrel. In clinical trials, it worsened a few cases of multiple sclerosis. In the great majority of patients the risk is outweighed by the drug's potential benefits.
• Rarely patients may develop other unusual immune reactions, including rashes, while on Enbrel.
• It may affect a person's ability to fight infections. Physicians are encouraged to exercise caution when considering the use of Enbrel in patients with a history of recurring infections.
• It is possible medications that inhibit or block TNF-alpha can allow pre-existing cases of tuberculosis (TB) to activate. Many physicians now require that potential drug recipients have a clear test for TB before beginning active treatment.
• There is a risk of serious, even life-threatening, infections in some people, especially if their immune system is already compromised. The drug may be temporarily discontinued in people who have active infections, such as lung infections or flu.
• The long-term side effects are unknown.

Other information

Because there are no effects on the blood or liver, there is no need for any blood tests to monitor Enbrel.

Toxicities

There are no known significant drug interactions.