CRN responds to FDA’s sudden policy change on supplements containing N-acetyl-L-cysteine

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The Council for Responsible Nutrition (CRN; Washington, D.C.) has responded to FDA regarding recent warning letters from the Agency alleging that N-acetyl-L-cysteine (NAC) is not a dietary supplement, and therefore prohibited from being marketed as such under the Federal Food, Drug, and Cosmetic Act (FDCA). It is CRN’s opinion that the policy is legally invalid and represents a drastic departure from its previous policy that has allowed manufacturers to safely market products with NAC as supplements.

FDA asserted in multiple warning letters that NAC was approved as a new drug in 1963, and was not to the Agency’s knowledge marketed as a dietary supplement before that time. This would mean that NAC does not qualify for a drug preclusion clause, and is therefore unlawful as a dietary supplement under Section 201(ff)(3)(B)(i) of the FDCA. In its letter to FDA, CRN argues that the sudden policy change is invalid because it unclear whether FDCA section 201(ff)(3)(B)(i) applies to NAC because the records of NAC’s drug approval contains unreliable and conflicting information. For example, the warning letters cite a 1963 date for drug approval, while a different document CRN found states that NAC was approved as a drug in 1985.

CRN also argues that NAC drugs approved prior to 2016 appear to be comprised of different forms of NAC compared to those found in dietary supplements. According to CRN, NAC drug approval records indicate that no NAC drugs were approved for oral use until 2016, well after supplement companies began marketing NAC in supplements. Additionally, CRN argues that interpreting FDCA section 201(ff)(3)(B)(i) to prohibit the marketing of supplements containing NAC, “violates the well-established presumption against statutory retroactivity.”

CRN’s full letter can be viewed here.