FDA SMOKING CESSATION EFFICACY STANDARD FOR OTC TABMINT

FDA SMOKING CESSATION EFFICACY STANDARD FOR OTC TABMINT (silver acetate) chewing gum does not correspond to the OTC advisory panel's recommendations, Edgefield Corp. maintained in an Oct. 27 letter to FDA. Responding to a May 28 letter from FDA, Edgefield President Joel Lund specifically objected to FDA's statement that a three weeks abstinence from smoking has always been considered a basic requirement for demonstrating efficacy. "This provision was not specified in the [OTC] advisory panel report, and was never mentioned in the correspondence relating to our 'well-written' proposed protocol," Lund stated. Lund argued that the panel report "specifies that effectiveness should be established at the end of three weeks, not during this period." He noted that after two years consideration, FDA advised Edgefield that the protocol for its smoking deterrent chewing gum was "well written." Lund said the protocol "specifically stated . . . that the principal objective of this protocol is to determine whether silver acetate . . . can cause complete cessation of smoking . . . at the end of the three week period." He added that "there is absolutely no indication in any of the FDA correspondence that this was not an acceptable criterion." The agency stated in its May letter, however, that it interpreted the protocol to mean that "anyone who did not abstain from smoking after beginning the study would be considered a treatment failure," Lund said. Tabmint gum is a product of the Danish firm Fertin Labs, which retained Edgefield Corp. to process Tabmint through FDA. Fertin is currently negotiating with Purdue Frederick for Purdue to market Tabmint in the U.S. once the product obtains Category I status. In an Oct. 30 letter to FDA, Purdue said it "will undertake the required studies to show efficacy" of Tabmint and that it is "in the process of finalizing protocols." FDA's tentative final monograph for OTC smoking deterrent products, published in July 1985, placed silver acetate in Category III. Lund also suggested that the agency's efficacy requirements for Tabmint are more stringent than they were in approving Merrell Dow's Rx Nicorette chewing gum. For instance, he said FDA told Edgefield in May that smoking had to cease "within the first 24 to 48 hours" for efficacy to be demonstrated. By contrast, he said the suggested tapering off period in the Nicorette SBA (Summary Basis of Approval) is considerably longer -- four weeks abstinence during a five to seven weeks study period. For Tabmint, "if a subject must be abstinent for three weeks on a three-week test, obviously there is no allowance for a tapering off period," Lund stated. In order to confirm compliance with the agency's efficacy requirements, Lund said the company attempted to show that the "quitters" in the study remained abstinent for four weeks. "We found 22% of those who completed the test had stopped smoking and that about half the quitters had started smoking again after four months," Lund reported. He said FDA told the firm that their results, obtained from oral statements, were not sufficiently documented. For Nicorette, he maintained, FDA "had not insisted on documented proof in matters of mechanics of action, toxicity (including carcinogenicity), systemic effects, etc." Lund questioned FDA's "marked preferential treatment of Nicorette as compared with Tabmint." He observed: "The first Tabmint monograph (indicating effectiveness) was filed 5/21/76 -- that for Nicorette on 3/14/81. The panel report, suggesting testing procedures, was published 5-1/2 years later -- 1/5/82. It took two years more to arrive at a suggested protocol (your feedback letter of 2/6/84). By that time FDA had processed and issued the Nicorette SBA -- 1/13/84 -- elapsed time, 34 months." Lund noted that the patent for Tabmint was issued in 1975 and thus 11 of the 17 years of patent life have expired.