SMITHKLINE's RIDUARA WILL ENTER U.S. ANTIARTHRITIC CLASS WITH 1-B

SMITHKLINE's RIDUARA WILL ENTER U.S. ANTIARTHRITIC CLASS WITH 1-B therapeutic rating from FDA, indicating an assessment of the oral gold product as a modest therapeutic advance. FDA approved Ridaura (auranofin) on May 24 after a three-and-a-half year NDA review. SmithKline filed the NDA in October 1981. Ridaura will carry labeling identifying the product as secondary treatment for rheumatoid arthritis patients who have not responded to one or more other nonsteroidal anti-inflammatory agents. FDA estimates that about 2 mil. Americans are under care for rheumatoid arthritis, "more than 200,000 of them may be receiving injected gold." The approved labeling states that Ridaura is "indicated in the management of adults with active, classical, or definite rheumatoid arthritis who have had an insufficient therapeutic response to, or are intolerant of, an adequate trial of full doses of one or more nonsteroidal anti-inflammatory drugs." The labeling is very close to the proposed wording discussed at an FDA advisory cmte. review of the drug in October ("The Pink Sheet" Oct. 29, p. 5). SmithKline intends to introduce the drug to the medical community with two different letters -- one aimed at users of the existing injectable disease-modifying antirheumatic drugs (DMARDS), and one to physicians who have not previously used that class of product. With Ridaura, SmithKline has the difficult task of carefully introducing a significant new therapeutic approach to a major disease market. The FDA advisory cmte. expressed concerns about the potential for undetected reactions to the gold treatment due to the convenience of the oral dosage form. In its May 24 press release announcing approval of Ridaura, SmithKline noted that patients should be monitored on a monthly basis. FDA said: "With the oral dose, weekly visits to the doctor for gold injections will not be necessary, but careful monitoring for reactions to the gold will still be needed at least once a month." The primary initial market for the drug, according to SmithKline's comments at the October advisory cmte. meeting will be rheumatologists and physicians experienced with the injectable formulations. A SmithKline representative told the October advisory cmte. meeting that the product would be focused on "physicians who are experienced in the treatment of rheumatoid arthritis, and more than that, are used to introducing second-step rheumatoid therapy." FDA noted that SK&F has "prepared patient information sheets for distribution by the prescribing physician and the dispensing pharmacist." Comparing oral versus injectable gold, SmithKline stated that "in clinical trials the dropout rate due to lack of therapeutic effect was lower among patients on injectable gold, but the dropout rate due to side effects was lower for Ridaura patients." The firm also said that "while no drug reverses the damage produced by rheumatoid arthritis, Ridaura, like injectable gold, may slow the progression of the disease process." Shipments to whslrs. will begin the week of June 3. According to SmithKline, the cost of one day's therapy is $1. The usual dose of the drug is 6 mg daily, given either in divided doses of 3 mg or one dose of 6 mg. The product will be packaged in bottles of 60 caps (3 mg). The May 24 approval is FDA's second major drug approval in three weeks. Merrell Dow's Seldane non-sedating antihistamine was approved on May 8. The NDA activity on major new drugs is not unusual at the end of the busy spring cycle. There also is a tendency to clear approvals before a topside change at the agency.