Warning Letter to a German Company - When regulatory Differences between the EU and the US become a Trap

In Europe, conventional antiperspirants are generally classified as cosmetics and are not regulated under medicinal products legislation. The decisive factor is that, under the definition of a cosmetic product, they are understood as products intended to cleanse, perfume, change appearance, or protect against body odor. The primary focus is therefore on a cosmetic benefit, such as reducing unpleasant odors.

In the United States, the classification is considerably stricter: Antiperspirants that inhibit perspiration are classified as over-the-counter (OTC) drugs. They affect a bodily function - sweat secretion - and therefore go beyond a purely “deodorant effect,” which merely binds or masks odors.
As a result, antiperspirants in the United States are subject to drug-quality requirements, including Current Good Manufacturing Practice (CGMP), approval or compliance with the applicable OTC monograph, and correct labeling as a drug.

It is against this background that the following FDA Warning Letter issued to Thomas Brunner Hygiene GmbH should be understood.

The Warning Letter

The FDA Warning Letter issued to Thomas Brunner Hygiene GmbH criticizes the manufacture and marketing of syNeo antiperspirants intended for the U.S. market. The company is registered with the FDA as an OTC drug manufacturer. As part of a records review under Section 704(a)(4) of the FD&C Act and an examination of the product labeling, including the company’s website, the FDA identified serious deficiencies.

Deficiencies in Manufacturing and Quality Assurance

With regard to GMP, the FDA primarily criticizes the fact that the finished products are not adequately tested before release. There are no reliable assay methods for the active ingredients, meaning that the identity and strength of the active components have not been scientifically substantiated.

In addition, adequate process and cleaning validation is lacking. The facility relies essentially on the final outcome - the “final inspection result” - without systematically demonstrating the control of critical process parameters and without validated, reproducible cleaning procedures for non-dedicated equipment.

Controls of raw materials are also inadequate. High-risk components such as glycerin are not consistently tested for diethylene glycol and ethylene glycol in accordance with USP requirements. Furthermore, the quality of the water used is not assured through a structured monitoring program in line with the USP requirements for water. Finally, there is no robust stability program incorporating stability-indicating methods and meaningful data covering the entire shelf life.

Overall, the FDA therefore considers the products to be “adulterated” because the methods, equipment, and controls do not comply with CGMP requirements.

Unapproved New Drug and Misbranding

At the same time, the FDA determined that the syNeo antiperspirants do not comply with applicable drug regulations. Through “Drug Facts” labeling and claims such as “Reduces underarm perspiration,” the products are clearly marketed as drugs.

In the United States, OTC antiperspirants are subject to OTC Monograph M019. Although aluminum chlorohydrate and aluminum chloride are each individually covered by the monograph, the syNeo products use them in combination - a combination that is expressly not provided for under the monograph.

The products therefore do not meet the conditions of the monograph, are not GRASE - generally recognized as safe and effective - and are considered “unapproved new drugs” for which no approval has been obtained. At the same time, they are considered “misbranded” because they violate the statutory marketing and labeling requirements.

The FDA requested that the company determine the root causes of these deficiencies, implement comprehensive corrective and preventive actions, and respond in writing within 15 business days.

Until the violations have been demonstrably corrected, the FDA may withhold approval of applications listing Thomas Brunner Hygiene GmbH as the manufacturer and may refuse entry into the United States for products manufactured at this facility.

In view of the breadth of the deficiencies, the FDA expressly recommends obtaining support from a qualified GMP consultant. However, overall responsibility remains with the company’s management.

Further details are available directly in FDA's Warning Letter .