PFIZER CHALLENGES STATUS OF TROLAMINE SALICYLATE (ASPERCREME)
• By The Pink Sheet
PFIZER CHALLENGES STATUS OF TROLAMINE SALICYLATE (ASPERCREME) under the OTC Review. In a Jan. 10 letter to FDA, Pfizer asserted that "a legitimate question exists as to how the ingredient could remain in the current OTC Review." Pfizer maintained that trolamine "does not appear to fit in either of the [OTC External Analgesic] Monograph's two defined pharmacologic classes of external analgesic active ingredients. There is nothing in the scientific record to suggest that trolamine salicylate acts to depress cutaneous receptors or otherwise is effective as an 'analgesic, anesthetic, and antipruritic' ingredient . . . Nor is there a claim by proponents that the ingredient is a 'counter-irritant'". In the Jan. 10 letter, Pfizer also objected to a previous letter to the agency from Thompson Medical. In an Oct. 16 submission, Thompson argued that two 1984 studies on trolamine performed for Pfizer provided evidence to support a Category I efficacy determination for the product ("The Pink Sheet" Nov. 18, T&G-10). One of the 1984 studies, conducted by Techni-Med Consultants, Inc., compared three products: a topical 10% trolamine salicylate cream and two placebo tablets; two aspirin tablets and a placebo cream; and placebo tablets and placebo cream. Thompson cited a Pfizer document that stated that, if the trend continued, statistical significance would occur when N = 60. With 23 patients, however, Pfizer reported that cream and tablets did not relieve pain to a statistically significantly greater degree than the placebos did. Pfizer told FDA that "the abandoned Techni-Med study was obviously producing irrational results in that the positive control, orally ingested aspirin, was shown to be ineffective versus its placebo on the 23 subjects evaluable at the preliminary analysis." Pfizer said "additional concerns about the poor quality of the study were also evident; for example, a large percentage of the 23 subjects continued to use concomitant medications to treat other chronic conditions during the study." Therefore, Pfizer concluded, "the margin note of a possible trend towards statistical significance with 60 evaluable subjects was pure conjecture" as it omitted to consider the major flaws in the study, and was not included in the preliminary analysis report. Thompson Medical had also cited a Pfizer market survey of 5,000 rub and liniment users to show that "45% of Aspercreme users agreed stongly that Aspercreme is effective to relieve arthritic pain, while less than half as many, or 20%, of Ben-Gay users agreed with the statement as to Ben-Gay." Pfizer asserted that FDA has previously stated that market research studies are insufficient to constitute adequate proof of effectiveness. Pfizer further contended that the statistics quoted by Thompson from the study are "out of context and misleading." Pfizer stated that "out of 5,000 people telephoned, 176 had tried Aspercreme. Of those, 54 people were regular users (a 69% majority did not remain regular Aspercreme users). The percentages given in the Thompson letter apply only to the 54 regular users, and ignore the fact that among the 69% majority, only a small number of the respondents gave the quoted 'strong' response as to the efficacy of Aspercreme." FDA recently denied Thompson Medical's request to make a final determination on the status of the drug as an OTC external analgesic. In a Nov. 21 letter to FDA OTC Division Director William Gilbertson, Thompson Medical noted that a Federal Trade Commission order prevents the promotion of its trolamine salicylate products but "does provide that it will accept FDA final approval" of the drug as Category I or two well-controlled clinical studies. On the basis of two studies it submitted in September, Thompson Medical requested that "FDA assert its primary jurisdiction by indicating that it is reviewing the new evidence and expects that trolamine salicylate in all probability will be placed in Category I."
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