PCMX ACTIVITY AGAINST COMMON ATHLETE's FOOT FUNGI IS NECESSARY

PCMX ACTIVITY AGAINST COMMON ATHLETE's FOOT FUNGI IS NECESSARY for the ingredient to move from Category III to Category I, FDA told W.F. Young at a July 31 OTC feedback meeting. The agency noted that a study submitted by Young evaluated the drug's efficacy against T. tonsurans, which FDA staffer C. Carnot Evans characterized as a "highly unusual" cause of tinea pedis. "I think there is a consensus that in any kind of evaluation of antifungal products there should be a spectrum of organisms, particularly involving those that are well known and are recognized to be [in] a cause and effect relationship in tinea pedis," Evans asserted. He cited antifungal testing guidelines developed by FDA's Rx Dermatology Drugs Advisory Cmte. in June 1984 which state: "Since tinea rubrum is considered one of the most common organisms found in tinea pedis and one of the most difficult to erradicate, a significant number of the clinical cases in each study should be culture positive for T. rubrum at the initial visit." The meeting was held at the request of the company as a follow-up to a June 10 feedback letter from FDA. Commenting on Young's study, which found 46 of 53 (86.6%) of subjects yielding T. tonsurans fungal isolates from the feet, FDA stated in its letter that one published study "indicates that only 5% to 15% of pedal lesions yield T. tonsurans" ("The Pink Sheet" June 24, T&G-81. W. F. Young consultant Ronald Pinkerton, MD, University of Connecticut School of Medicine, suggested that mycology might be changing. "I don't know of any other clinical disease that doesn't have a changing etiology at the genesis of clinical expression over 30 years," Pinkerton said. Evans responded that the idea that the cause of tinea pedis is changing is "unsupportable." He said no other companies that have received antifungal approvals have had spectrums like those submitted by Young. Company consultant Richard Tilton, PhD, University of Connecticut School of Medicine, asked when the "last, naturally occuring, complete identification of the mycology of the pathogenesis of athlete's foot" was conducted. He commented: "I can well understand your desire to have the product tested against a range of organisms. What I cannot understand, ladies and gentlemen, is your inability, or your refusal, to recognize what I consider to be a valid mycological analysis of tinea pedis in the environment. It is mindful of five years ago when people began to see Kaposi's sarcoma [and said] 'I haven't seen Kaposi's sarcoma in 20 years, therefore it doesn't exist.'"