BEECHAM TOPICAL BACTROBAN APPROXIMATES SYSTEMIC ANTIBIOTIC EFFICACY FOR IMPETIGO, CMTE. SAYS; COMPARATIVE DATA TO SYSTEMIC DRUGS ENCOURAGE

Beecham's Bactroban (mupiricin) is as effective in the treatment of impetigo as systemic antibiotics, FDA's Dermatology Drugs Advisory Cmte. concluded at its June 24 meeting. The cmte. recommended by a vote of nine-to-one that the topical product should be approved by FDA.

The cmte. based its recommendation on the results of two clinical trials presented by Beecham that showed similar mupiricin efficacy rates. Bacteriological evaluation in one double-blind, placebo controlled trial with 100 impetigo patients revealed that in 92% of the mupiricin-treated patients the pathogen was eliminated. The firm also reported, in that same trial, when clinically evaluated, 98% of the mupiricin-treated patients' impetigo was either cured or improved.

The cmte. voted to recommend approval of Bactroban despite the lack of a clinical trial in which a systemic antibiotic was used as a control. However, the cmte. adopted a motion from cmte. member Clinton Miller, PhD, Medical University of South Carolina, encouraging the use of active systemic control groups for future topical impetigo products.

The cmte. voted seven-to-three in favor of Miller's motion that the cmte. recommend to the FDA that in subsequent studies further information pertaining to follow-up be included. That information, Miller said, should include "the instance of relapse, the instance of resistant organisms and other physiological abnormalities," and the use of systematic active control groups where possible.

Noting that "there is data to show that pseudomonic acid [formerly mupiricin's generic name] is more effective than the vehicle in the treatment of impetigo," FDA asked the cmte. to answer the question, "Can you recommend that pseudomonic acid be approved for this indication in the abscence of information showing that its effect approximates that of systemic antibiotic therapy?"

In answering FDA's question, the cmte. considered three issues: whether or not to recommend approval of mupiricin based on the firm's data; whether or not mupiricin efficacy was sufficiently established in the absence of a systemic antibiotic controlled study; and whether or not to require a positive controlled study with a systemic antibiotic for topicals seeking a primary skin infection indication.

FDAer Carnot Evans, MD, explained that the agency's question to the cmte. was geared towards getting feedback not only on mupiricin, but on whether systemic controlled studies were needed for any topical antibiotic indicated for primary skin infections. "Not only for this drug, but in general, how are we going to make decisions about the efficacy of this type of topical antibiotic," Evans asked the cmte.

Explaining why he recommended approval, Cmte. Chairman James Rasmussen, MD, University of Michigan Medical School, said mupiricin's "efficacy rate, depending on how you want to look at it.. .really was 75% to 95% which I think would approximate most results" you would see with systemic antibiotics. "So I feel reasonably comfortable with the information although we have not critically examined it. I don't feel that a comparison study is necessary."

Cmte. member Lowell Goldsmith, MD, University of Rochester Medical Center, voted against approval of mupiricin because of "the fuzziness of the clinical diagnosis of impetigo." He said: "If I saw a nice proper study with impetigo and quantitative bacteriology and nasal cultures coming in I don't think there would be any problem." Goldsmith did not support requiring systemic antibiotic control. He explained "Putting another type of study in here and trying to tell the difference between whether it's 5% better or 5% less" effective, is not "going to make my decision easier.