The Natural Products Association (NPA) on Tuesday voluntarily dismissed a complaint against FDA regarding NAC (N-acetyl-L-cysteine) products marketed as dietary supplements.

In a Nov. 1 filing in the U.S. District Court for the District of Maryland, a lawyer representing NPA, Richard Oparil, dismissed without prejudice all claims against the defendants. That gives NPA the opportunity to revive claims against FDA in a fresh lawsuit if it butts heads down the road with U.S. regulators over NAC.

NPA sued FDA in December 2021 after the agency declared in 2020 warning letters that NAC could not be lawfully marketed as a dietary supplement since it was first approved as a drug in 1963.

The agency’s declarations caused various business disruptions to the NAC marketplace, industry stakeholders said, which included a decision by Amazon last year to stop selling NAC products. Meanwhile, industry stakeholders provided FDA evidence that NAC has been marketed in nutritional products since the early 1990s.

On March 31, FDA published a comprehensive response to two NAC citizen petitions filed by NPA and the Council for Responsible Nutrition (CRN). While FDA reiterated its view that NAC is excluded from the definition of a dietary supplement, it outlined plans to exercise “enforcement discretion” regarding NAC-containing products.

Related:FDA issues final ‘enforcement discretion’ guidance on NAC

Those plans were implemented in draft and final guidance documents. The final guidance paved the way for NAC to be sold in the U.S. as a dietary supplement without fear of repercussions from FDA—so long as the products are otherwise compliant with FDA regulations and the Federal, Food, Drug & Cosmetic Act (FDCA).

“When the industry suffered significant economic harm as a direct result of the agency’s long and inexplicable delays on a NAC regulatory path, NPA and its leadership led the way forward because of our commitment to the industry and holding FDA accountable,” NPA President and CEO Dan Fabricant said in a news release, announcing dismissal of the lawsuit. “We hope the agency uses this as a learning experience and handles other outstanding issues like CBD more appropriately.”

NAC exports

NPA is still working with FDA to ensure NAC products can be exported to other countries.

According to an FDA webpage on food export certificates, NAC-containing products labeled as dietary supplements should not be included in a “certificate of free sale” application but may qualify for a different certificate to facilitate exports. FDA advises firms to submit an application for NAC-containing products to start the process, after which the Office of Dietary Supplement Programs (ODSP) will be in touch with the applicant for next steps.

Related:Amazon resumes sales of NAC supplements

“For exports, FDA has initiated a process and we continue to work directly with the agency and foreign governments to ensure exports on NAC return to levels prior to this series of events,” Fabricant added in the news release. “Thankfully, as a direct result of our lawsuit, the industry can sell domestically and internationally once again, maintain insurance, and ensure the FDA is consistent and meeting its basic regulatory obligations.”

FDA's ODSP declined to comment on the lawsuit’s dismissal and the export certificate issue.