OTC DEXTROMETHORPHAN: NDMA REQUESTS "TWO WEEK WASHOUT" PRECAUTION
OTC DEXTROMETHORPHAN: NDMA REQUESTS "TWO WEEK WASHOUT" PRECAUTION be added to a proposed warning against concomitant use of the OTC antitussive agent and prescription monoamine oxidase inhibitors (MAOIs). FDA proposed the warning statement on June 19 ("The Pink Sheet" June 22, T&G-4). In Oct. 2 comments on the agency's proposal, the Nonprescription Drug Manufacturers Association suggested that FDA add a statement not to use products containing dextromethorphan "for two weeks after stopping use of a MAOI without first consulting your doctor." "MAOIs" used clinically in the U.S. are irreversible or only partially reversible enzyme inhibitors," NDMA said. "Recovery of MAO activity after irreversible inhibition may require up to two weeks following withdrawal of a MAOI." Inclusion of a two week washout period would also "help ensure that patients will not discontinue the use of [MAOIs] in order to use" the over-the- counter products, NDMA added. The OTC drug trade association's comments indicate support for FDA's decision to require a warning against dextromethorphan/MAOI reactions. Agency officials cited their work with regulated industry on the issue during an April congressional hearing as an example of FDA's ability to respond to newly-discovered health risks associated with OTCs ("The Pink Sheet" May 4, p. 12). NDMA suggests two other changes to the proposal in its Oct. 2 comments. First, the association said the proposed warning should mention only "conditions that are approved uses of the referenced Rx drug and where the approved drug therapy for that condition has been determined to have a clinically significant interaction with the OTC drug of interest." FDA's current proposed description of MAOIs as "certain drugs for depression or pshychiatric or emotional conditions, or Parkinson's disease" is "overly broad," NDMA declared. The "only approved use for nonselective MAOIs is: depression," NDMA said. "As a matter of labeling policy when developing OTC label language, FDA should include only those aspects of Rx labeling that are formally approved," NDMA maintained. "Creating a situation where the OTC label is constantly in flux to account for potentially very rare adverse reactions based on ever-changing unapproved uses for a particular class of Rx drugs abuses the OTC label." FDA proposed adding a reference to Parkinson's disease in August ("The Pink Sheet" Aug. 10, T&G-8). Somerset Pharmaceuticals markets a selective MAO B inhibitor, selegiline Eldepryl), for treatment of Parkinson's. However, NDMA maintained, "the Rx package insert explicitly states that drug-drug interactions are not likely to occur between selegiline and OTC drugs." In separate Oct. 2 comments, Somerset noted that it has received no reports of suspected drug interactions involving Eldepryl and OTC nasal decongestants containing a sympathomimetic amine. The remaining change requested by NDMA is that FDA delete the final sentence of the proposed warning: "If you are uncertain whether your prescription drug contains an MAOI, consult a health professional before taking this product." NDMA believes that "a general informational statement urging consumers to use common sense should not be a part of the MAOI/OTC drug-drug interaction precautions. Not only does it add lengthy wording to already crowded OTC cough/cold labeling, but it also is inappropriately placed as part of a specific warning."
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