SELEGILINE/OTC COUGH-COLD DRUG INTERACTION DATA ARE SOUGHT BY FDA

Executive Summary

SELEGILINE/OTC COUGH-COLD DRUG INTERACTION DATA ARE SOUGHT BY FDA in Aug. 6 Federal Register notices. The three separate notices extend to Oct. 5 the comment period for FDA's proposed warning statement on interactions between prescription monoamine oxidase inhibitors and OTC antitussives, nasal decongestants, or bronchodilators containing dextromethorphan or sympathomimetic amines. Selegiline (Eldepryl) is a selective MAO B inhibitor marketed by the Mylan/Bolar joint venture Somerset Pharmaceuticals for treatment of Parkinson's. On June 19, FDA proposed to amend the OTC Antitussives Final Monograph to add a "drug interaction precaution" against use of dextromethorphan-containing products and prescription MAO inhibitors. The agency also proposed to change the language of the MAOI warnings required by the Nasal Decongestants tentative final monograph and the Bronchodilators Final Monograph ("The Pink Sheet" June 22, T&G-4). However, FDA "did not address selegiline or MAO B inhibitors in the earlier proposal," the Aug. 6 notices state. FDA "has not received any reports of an interaction between selegiline" and dextromethorphan or sympathomimetic amines. It "invites any interested person with knowledge of such an interaction having occurred to provide that information to the agency." If FDA decides to include selegiline in the warning, the required language would change slightly, the notices advise. Instead of characterizing MAOIs as "certain drugs for depression, psychiatric or emotional conditions," the new warning statement would say "certain drugs for depression, psychiatric or emotional conditions, or Parkinson's disease." FDA presumably might also consider relabeling Eldepryl to warn of the potential interaction. "At doses greater than 10 mg per day and, perhaps, at lower doses in some people, selegiline's selectivity [for MAO B rather than A] decreases," FDA also pointed out, adding: "Other, apparently more specific, MAO B inhibitors are now under development." The development of the dextromethorphan warning was discussed at an April congressional hearing as an example of FDA's ability to work with regulated industry to address health risks associated with OTC products. FDA had already told manufacturers about the proposal so that they could begin to incorporate the change without waiting until the end of the notice and comment period ("The Pink Sheet" May 4, p. 12).