This article is part of the Arthritis Archives.
Dateline: November 5, 1998
On November 2, 1998, the U.S. Food and Drug Administration announced the approval of the long-awaited, breakthrough drug Enbrel, generic name etanercept, for the treatment of rheumatoid arthritis (RA).
Enbrel (etanercept) is the first in a new class of rheumatoid arthritis drugs referred to as "biologic response modifiers". Enbrel is a totally new approach to the treatment of rheumatoid arthritis and works by interrupting the inflammatory process of the disease.
Action of Enbrel
The mode of action of Enbrel involves the binding of TNF (tumor necrosis factor). TNF is one of the cytokines or proteins which play a pivotal role in the reactions which cause the inflammatory process of rheumatoid arthritis. Enbrel competitively inhibits the binding of TNF to TNF receptor sites. The TNF bound to Enbrel is biologically inactive resulting in reduced inflammatory activity.
Indication and Dosage
Enbrel is indicated for "the reduction in signs and symptoms of moderately to severely active rheumatoid arthritis in patients who have an inadequate response to one or more disease-modifying anti-rheumatic drugs (DMARDs)". Enbrel can be used together with methotrexate in patients not responding to methotrexate alone. The dosage for adults is 25 mg. given two times a week as a subcutaneous injection.
More than 1,000 people have participated in clinical trials of Enbrel. In one study of 234 patients with advanced rheumatoid arthritis, 59 percent who took Enbrel for 6 months showed significant improvement compared to 11 percent who were given placebo. About 40 percent of the Enbrel patients saw their symptoms decrease to half. In another study which combined Enbrel with methotrexate, 71 percent of patients taking both drugs experienced improvement compared to 27 percent who took only the methotrexate.
Mild to moderate injection site reactions were the most commonly reported adverse effect in Enbrel trials. Long term effects of Enbrel use or the potential for serious infection, malignancy, or autoimmune disease are not known.
Marketing and Cost
Immunex Corporation and Wyeth-Ayerst Laboratories will market Enbrel in North America while other Wyeth-Ayerst affiliates will market the drug outside North America. The drug is expected on pharmacy shelves within days. A prescription is required to obtain the drug. The cost of Enbrel will be $220 per week ($110 per vial of Enbrel).
Sources: Rheumatoid Arthritis Drug Wins OK, AP Online, 11/02/98; Enbrel Receives FDA Approval For Treatment Of Rheumatoid Arthritis, PRNewswire, 11/02/98; New Rheumatoid Arthritis Drug Approved, UPI, 11/03/98
First published: 11/05/1998