TNF alpha is a cytokine, a protein that is produced during the inflammatory response. TNF alpha is involved in inflammation from two perspectives. It is not only the product of inflammation; it also helps perpetuate and promote inflammation. Increased levels of TNF are found in several inflammatory conditions including rheumatoid arthritis, psoriatic arthritis, and ankylosing spondylitis. Drugs that block tumor necrosis factor (TNF) have been found to be particularly effective for the treatment of these serious forms of inflammatory arthritis.
The first anti-TNF drug approved for such use was etanercept (Enbrel).
Etanercept is a synthetic (man-made) protein that binds to TNF alpha. It acts like a sponge to remove most of the TNF alpha molecules from the joints and blood. This prevents TNF alpha from perpetuating inflammation and the pain, tenderness and swelling of joints in patients with different types of arthritis.
Etanercept reduces the signs and symptoms of rheumatoid arthritis, the arthritis of psoriasis, and ankylosing spondylitis. It also prevents the progression of joint destruction in patients with rheumatoid arthritis and the arthritis of psoriasis.
Etanercept is usually used in combination with methotrexate in patients who do not respond adequately to methotrexate alone.
Etanercept comes in two different preparations. The first is a powder that must be reconstituted (mixed) with a diluent. This comes as a 25 mg dose. The second is as a premixed syringe containing 50 mgs of etanercept. Etanercept must be refrigerated. The drug is given as a subcutaneous injection. Dosing will vary according to disease severity and body size.
Because etanercept reduces the immune response, it should not be administered with live vaccines.
Etanercept is not recommended for use in pregnant or nursing women.
The most common side effects are mild to moderate itching, pain, swelling and redness at the site of injection. Headache, dizziness, nose and throat irritation also occur.
TNF alpha has an important role in the response of the immune system to infections. Blocking the action of TNF alpha with etanercept may worsen or increase the occurrence of infections, and patients with serious infections should not receive etanercept. Etanercept should be discontinued if a patient develops a serious infection. It should not be given to patients with active infections or who have an allergy to its components. Etanercept should be used with caution in patients prone to infection, such as those with poorly controlled diabetes.
Since etanercept has entered the market, there have been reports of multiple sclerosis, myelitis, optic neuritis in patients using the drug. Etanercept is not recommended for persons with preexisting disease of the central nervous system (brain and/or spinal cord) or for those with multiple sclerosis, myelitis, or optic neuritis. Rare cases of potentially serious low blood counts (pancytopenia) have been reported in patients using etanercept.
Monitoring should be done according to guidelines set by the rheumatologist.
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