Mercury Data On Drugs, Supplements Requested By FDA

Data on drug, food and dietary supplement products that contain "intentionally introduced" mercury compounds are requested by FDA in a Dec. 14 Federal Register notice. The agency asks that data and general comments be submitted by March 15.

FDA is soliciting "both quantitative and qualitative information about the mercury compounds" in marketed drug and food products. Such compounds include mercurous chloride, mercuric chloride, phenylmercuric acetate and thimerosal.

The agency's listing and subsequent analysis of mercury compound-containing products was mandated in a provision of the FDA Modernization Act ("The Tan Sheet" Nov. 17, 1997, p. 7).

Both active and inactive mercury compound ingredients are applicable, assuming they are intentionally included in a product. FDA requests manufacturers submit the commercial name as well as the chemical name, the Chemical Abstract Service registry number and the CAS preferred chemical name of any mercury compound.

Quantitative amounts should be stated as either "quantity per dosage unit or per quantity of product (e.g., ounce or gram)" and whether the amount is "calculated on a weight to weight (w/w) or weight to volume (w/v) basis, where applicable," FDA says.

The agency also requests data on the "purpose" of the mercury compound in a product, the pharmacologic use if it is an active ingredient or the "function" if inactive, a copy of the labeling and the approximate amount of the compound "used annually in manufacturing the product."

Various mercury compounds, both inorganic and organic, have been used in Rx and OTC drug products. OTCs containing compounds as active ingredients have included dandruff/psoriasis products, external analgesics, laxatives, skin bleaching products, ophthalmics, first aid antiseptics, antimicrobial diaper rash products and vaginal contraceptives.

FDA assigned non-monograph status to 17 mercury-related actives used in these products in a final rule published April 17 ("The Tan Sheet" April 27, p. 4). The agency said the ingredients are not generally recognized as safe and effective. The rule became effective Oct. 19, meaning the listed ingredients now should be removed from all marketed products.

FDA also has reviewed mercury compounds included in ophthalmic products as inactive ingredients. The final monograph for OTC ophthalmic drug products contains the language: "This product contains (name and quantity of mercury-containing ingredient) as a preservative. Do not use this product if you are sensitive to (select one of the following: 'mercury' or [insert name of mercury-containing ingredient] or any other ingredient containing mercury)."

Phenylmercuric acetate and thimerosal are used as preservatives in OTC nasal and opthalmic solutions, FDA notes, and phenylmercuric nitrate is found in some oral homeopathic drugs. In addition to drugs, foods and supplements, the request for data and information applies to homeopathic drugs and veterinary products.

Mercury is included in some dietary supplements sold in the U.S., as well as in traditional medicines. Cinnabar (mercuric sulfide) and calomel (mercurous chloride) have been used in traditional Chinese medicines "as a sedative and detoxicant and to treat constipation and edema, respectively," FDA points out.

The notice also cites a recent California Department of Health study that found five of 260 traditional Chinese medicines available at retail list cinnabar as an ingredient; 35 of 251 products examined for mercury content "were found to contain significant quantities of mercury."

Most of the mercury compound-containing products covered in the study did not mention the relevant compound on labeling. As a result, "it is not possible to determine whether the mercury in these products is intentionally added or is present as an unintended ingredient or contaminant," FDA states. "Other than this limited information, FDA is not aware of other uses of mercury in dietary supplements."

Information on human drugs should be sent to the Division of OTC Drug Products within the Center for Drug Evaluation & Research; data on foods and dietary supplements may be sent to the Center for Food Safety & Applied Nutrition Office of Special Nutritionals. CDER's Gerald Rachanaw (301-827-2222) and CFSAN's Sharon Ross (202-205-5343) can be contacted for further information.