FDA recently gave its most thorough explanation of how it interprets a provision that prohibits drugs in dietary supplements, lawyers at Hyman Phelps & McNamara say, and industry is worried that interpretation will hurt the development of supplement ingredients. The supplement measure is nearly identical to a recently added restriction on food, and the lawyers predict food ingredient development will be similarly affected.

FDA recently determined, in responding to a citizen petition filed by a pharmaceutical company, that a form of vitamin B6 is not a dietary supplement. FDA rejected pyridoxamine as a supplement because it has been authorized as a new drug for which substantial clinical investigations have been made public, and pyridoxamine was not marketed as a supplement nor food prior to the drug’s authorization.

Specifically, B6 has been the subject of an Investigational New Drug application and three substantial clinical investigations that have been made public. There is no “independent, verifiable evidence” of prior marketing of pyridoxamine as a food or dietary supplement, FDA said, and affidavits affirming prior marketing are inadequate.

“The rationale expressed by FDA in support of its determination with respect to pyridoxamine suggests that FDA is likely to adopt an interpretation of § 301(ll) that is much more favorable to the pharmaceutical industry than what many food and dietary supplement manufacturers have advocated,” the FDA Law Blog states. The blog is written by Hyman Phelps lawyers.

FDA’s determination doesn’t appear to allow for factors such as whether supplements include low doses of ingredients being studied as drugs or whether supplement makers market ingredients for uses different from what they studied for as drugs, said Ricardo Carvajal, a former FDA attorney.

The Council for Responsible Nutrition says a broad interpretation of the measure could lead drug companies to conduct trials solely to keep ingredients from being added to food and supplements.

The group states in an e-mail Wednesday (Jan. 28) that the agency’s decision could set a precedent that encourages drug companies to challenge the status of other dietary ingredients.

CRN recommends that supplement and food companies keep thorough records of ingredients and marketing materials.

“FDA’s decision suggests that companies need to produce even more extensive evidence supporting an ingredient’s marketing as a dietary supplement, including catalog and business records from more than 15 years ago,” CRN states. “Demanding that industry maintain these records, but failing to work with industry to develop an agreed-upon list of ‘grandfathered ingredients,’ places more burden on dietary supplement companies to be sure that they can substantiate that an ingredient has in fact previously been marketed as a dietary supplement.”

Food also will likely be affected the same. The FDA Amendments Act of 2007 added a measure to food law that is nearly identical to the provision prohibiting drugs in dietary supplements.