WARNING LETTER
Thomas Brunner Hygiene GmbH
MARCS-CMS 729018 —
July 24, 2026
Delivery Method:
Via Email Return Receipt Requested
Reference #:
320-26-106
Product:
Drugs
Over-the-Counter Drugs
Recipient:
Recipient Name
Thomas Brunner
Recipient Title
Managing Director
Thomas Brunner Hygiene GmbH
Carl-Benz-Strasse 7
Albershausen
73095
Baden-Württemberg
Germany
(b)(4)
Issuing Office:
Center for Drug Evaluation and Research (CDER)
United States
July 24, 2026
WARNING LETTER
Reference number: 320-26-106
Dear Mr. Brunner:
This Warning Letter advises you of significant violations identified during a U.S. Food and Drug Administration (FDA) review of your records.
These violations were identified and documented during review of your drug manufacturing facility, Thomas Brunner Hygiene GmbH, located at Carl-Benz-Strasse 7, 73095 Albershausen, Baden-Württemberg, Germany, FDA Establishment Identifier (FEI) 3035784232. This review was conducted under FDA’s statutory authority and public health responsibilities to protect the public from unsafe, ineffective, and poor quality drugs.
Your facility is registered with the United States Food and Drug Administration (FDA) as a manufacturer of over-the-counter (OTC) drug products. FDA has reviewed the records you submitted in response to our August 12, 2025, request and in subsequent correspondence, for records and other information pursuant to section 704(a)(4) of the Federal Food, Drug, and Cosmetic Act (FD&C Act) for your facility.
This Warning Letter summarizes significant violations of Current Good Manufacturing Practice (CGMP) regulations for finished pharmaceuticals. See Title 21 Code of Federal Regulations, parts 210 and 211 (21 CFR parts 210 and 211).
Because your methods, facilities, or controls for manufacturing, processing, packing, or holding of drugs as described in your response to our 704(a)(4) request do not conform to CGMP, your drug products are adulterated within the meaning of section 501(a)(2)(B) of the FD&C Act (21 U.S.C. 351(a)(2)(B)).
In addition, violations were identified and documented during a review of your product labeling, including your website at the internet address https://syneo.us/ website in April 2026. Based on our review, your “syNeo ANTI-PERSPIRANT PUMP SPRAY,” “syNeo ANTI-PERSPIRANT ROLL-ON,” “syNeo ANTI-PERSPIRANT WET WIPES,”“syNeo MAN ANTI-PERSPIRANT PUMP SPRAY,” “syNeo MAN ANTI-PERSPIRANT ROLL-ON,” “syNeo SOFT ANTI-PERSPIRANT PUMP SPRAY,” and “syNeo SOFT ANTI-PERSPIRANT ROLL-ON” (collectively “syNeo antiperspirant products”) are unapproved new drugs under section 505(a) of the FD&C Act, 21 U.S.C. 355(a). In addition, these products are misbranded under section 502(ee) of the FD&C Act, 21 U.S.C. 352(ee). As explained further below, introducing or delivering these products for introduction into interstate commerce is prohibited under sections 301(d) and (a) of the FD&C Act, 21 U.S.C. 331(d) and (a).
Violations of the Federal Food, Drug, and Cosmetic Act
The following are violations identified during our review. As a reminder, this is not an all-inclusive list of violations at your facility.
1. Your firm failed to have, for each batch of drug product, appropriate laboratory determination of satisfactory conformance to final specifications for the drug product, including the identity and strength of each active ingredient, prior to release (21 CFR 211.165(a)).
The records and information you provided did not demonstrate that you adequately tested your finished drug products before their release and distribution. For example, the documentation you provided did not include an assay test for active ingredient content in your finished drug products.
Testing is an essential part of CGMP to ensure that the drug products you manufacture conform to all predetermined quality attributes appropriate for their intended use. Drug products must be tested for identity and strength of the active ingredient before their release and distribution. Without adequate testing, you do not have scientific evidence to ensure that your drug products conform to appropriate specifications before their release.
In response to this letter, provide:
A list of chemical and microbial specifications, including test methods, used to analyze each batch of your drug products before a batch disposition decision.
An action plan and timelines for conducting full chemical and microbiological testing of reserve samples to determine the quality of all batches of drug product distributed to the United States that are within expiry as of the date of this letter.
A summary of all results obtained from testing the reserve samples from each batch. If such testing reveals substandard quality drug products, take rapid corrective actions, such as notifying customers and initiating product recalls.
A comprehensive, independent assessment of your laboratory practices, procedures, methods, equipment, documentation, and analyst competencies. Based on this review, provide a detailed plan to remediate and evaluate the effectiveness of your laboratory system.
2. Your firm failed to establish adequate written procedures for production and process control designed to assure that the drug products you manufacture have the identity, strength, quality, and purity they purport or are represented to possess. Your firm also failed to establish and follow adequate written procedures for cleaning and maintenance of equipment (21 CFR 211.100(a) and 211.67(b)).
Based on records and information your firm provided, you did not demonstrate that you adequately validated your manufacturing and cleaning processes.
Lack of Adequate Process Validation
Your firm lacks adequate process validation studies. You failed to provide sufficient data to demonstrate that appropriate controls and critical parameters are applied to ensure reproducibility of your drug manufacturing procedures. Your response indicated that you consider processes to be suitable “if the final inspection result is satisfactory,” and that you perform no further validation activities. Moreover, the test reports provided in your response did not include an assay test for active ingredient content.
Process validation evaluates the soundness of design and state of control of a process throughout its lifecycle. Each significant stage of a manufacturing process must be designed appropriately and must ensure the quality of raw material inputs, in-process materials, and finished drugs. Process qualification studies include intensive monitoring and testing throughout each significant process stage to characterize intra-batch variation and to evaluate batches to determine whether an initial state of control has been established.
Successful process qualification studies are necessary before commercial product distribution. Thereafter, ongoing vigilant oversight of process performance and product quality is necessary to ensure that you maintain a stable manufacturing operation throughout the product’s lifecycle.
See FDA’s guidance document
Process Validation: General Principles and Practices
at https://www.fda.gov/media/71021/download for general principles and approaches that FDA considers appropriate elements of process validation.
Lack of Adequate Cleaning Validation
The records and information your firm provided did not demonstrate that you have established adequate, validated procedures for cleaning nondedicated manufacturing equipment. Cleaning validation cannot be conducted without specific, reproducible cleaning procedures.
Inadequate removal of active ingredients and product residues from the surfaces of nondedicated manufacturing equipment can lead to contamination of drug products subsequently manufactured on that equipment.
In response to this letter, provide:
A detailed summary of your validation program for ensuring a state of control throughout the product lifecycle, along with associated procedures. Describe your program for process performance qualification and the ongoing vigilant monitoring of both intra-batch and inter-batch variation to ensure a continuing state of control. Also, describe your equipment and facility qualification program.
A timeline for performing process performance qualification (PPQ) for each of your marketed drug products. In addition, provide a risk assessment and any follow-up actions to be taken for the distributed drug products that were produced without the performance of any process validation studies.
Appropriate improvements to your cleaning validation program, with special emphasis on incorporating conditions identified as worst case in your drug manufacturing operation. These conditions should include but not be limited to the identification and evaluation of all worst case:
o Drugs with higher toxicities
o Drugs with higher drug potencies
o Drugs of lower solubility in their cleaning solvents
o Drugs with characteristics that make them difficult to clean
o Swabbing locations for areas that are the most difficult to clean
o Maximum hold times before cleaning
In addition, describe the steps that must be taken in your change management system before the introduction of new manufacturing equipment or a new product.
A summary of updated SOPs ensuring that an appropriate program is in place for the verification and validation of cleaning procedures for products, processes, and equipment.
3. Your firm failed to test samples of each component for identity and conformity with all appropriate written specifications for purity, strength, and quality (21 CFR 211.84(d)(1) and 211.84(d)(2)).
The records and information your firm provided did not demonstrate that you adequately tested the raw materials used to manufacture your drug products.
Products Containing High-Risk Drug Components
Your firm failed to test the identity of incoming components, such as glycerin, used to manufacture your drug products. Identity testing for glycerin and certain other high-risk drug components includes a limit test in the United States Pharmacopeia (USP) to ensure that the component meets the relevant safety limits for levels of diethylene glycol (DEG) and ethylene glycol (EG). Because you did not perform adequate identity testing on each shipment of each lot using the USP identification test that detects these hazardous impurities, you failed to ensure the acceptability of these components for use in the manufacturing of your drug product.
The use of ingredients contaminated with DEG or EG has resulted in various lethal poisoning incidents in humans worldwide. See FDA’s guidance document
Testing of Glycerin, Propylene Glycol, Maltitol Solution, Hydrogenated Starch Hydrolysate, Sorbitol Solution, and Other High-Risk Drug Components for Diethylene Glycol and Ethylene Glycol
at https://www.fda.gov/media/167974/download for help in meeting the CGMP requirements when manufacturing drugs containing ingredients that are at high risk for DEG or EG contamination.
Products Containing Water as a Component
Your firm has not demonstrated that the water used as a component in your drug products is suitable for use and meets the USP
(b)(4)
Water monograph. For example, you failed to provide evidence that you performed conductivity and total organic carbon testing of the water you used to manufacture your drug products.
Water is an ingredient in your drug products.
(b)(4)
water must be suitable for its intended use and must routinely be tested to ensure ongoing conformance with appropriate chemical and microbiological attributes.
In response to this letter, provide:
A commitment to provide DEG and EG test results, no later than 30 calendar days from the date of this letter, from testing retains for all lots of high-risk drug components used in the manufacture of drug products. Alternatively, if a retain of a component lot is unavailable, perform retain sample testing of all implicated finished drug product batches for the presence of DEG and EG.
A full risk assessment for drug products that are within expiry and that contain any ingredient at risk for DEG or EG contamination (including, but not limited to, glycerin). Take prompt and appropriate actions to determine the safety of all lots of the component(s) and any related drug product that could contain DEG or EG, including customer notifications and product recalls for any contaminated lots. Identify any additional appropriate corrective actions and preventive actions (CAPA) that will secure supply chains in the future, including but not limited to ensuring that all incoming raw material lots are from fully qualified manufacturers and are free from unsafe impurities. Detail these actions in your response to this letter.
A description of how you will test each component lot for conformity with all appropriate specifications for identity, strength, quality, and purity. If you intend to accept any results from your suppliers’ certificates of analysis (COAs) instead of testing each component lot for strength, quality, and purity, specify how you will robustly establish the reliability of your suppliers’ results through initial validation and periodic revalidation. In addition, include a commitment to always conduct at least one specific identity test for each incoming component lot. In the case of glycerin, propylene glycol, and certain additional high-risk components, we note that this testing includes the performance of parts A, B, and C of the USP monograph.
A procedure for your water system monitoring that specifies routine microbial testing of your water to ensure its acceptability for use in each batch of drug products produced by your firm.
The current action/alert limits for total counts and objectionable organisms used for your
(b)(4)
Water system.
A procedure governing your program for ongoing control, maintenance, and monitoring, ensuring that the system consistently produces water that meets
(b)(4)
Water, USP monograph specifications and appropriate microbial limits.
A comprehensive, independent review of your material system to determine whether all suppliers of components, containers, and closures are individually qualified, and whether the materials are assigned appropriate expiration or retest dates supported by appropriate data. The review should also determine whether incoming material controls are adequate to prevent the use of unsuitable components, containers, and closures.
A summary of your systems CAPA, based on a thorough review, to remediate the vendor-qualification program and prevent the use of unsuitable components, containers, and closures.
The chemical quality control specifications you use to test each incoming lot of high-risk drug components to determine their acceptability for use in manufacturing.
A summary of your program for qualifying and overseeing contract facilities that test the components and drug products you manufacture.
4. Your firm failed to establish and follow a written testing program designed to assess the stability characteristics of drug products (21 CFR 211.166(a)).
The records and information you provided did not demonstrate that the chemical and microbiological properties of your drug products remain acceptable throughout the labeled
(b)(4)
expiry period. For example, the stability data you provided includes only the results from a
(b)(4)
study performed between
(b)(4)
degrees Celsius, and a
(b)(4)
study at
(b)(4)
degrees Celsius. Moreover, the test methods do not appear to be stability-indicating.
Without adequate stability studies, you do not have scientific evidence to support whether your drug products meet established specifications and retain their quality attributes through their labeled expiry.
In response to this letter, provide:
A comprehensive, independent assessment and CAPA plan to ensure the adequacy of your stability program. The remediated program should include but not be limited to:
o Stability-indicating methods
o Stability studies for each drug product in its marketed container/closure system before distribution is permitted
o An ongoing program in which representative batches of each product are added each year to the program to determine if the shelf-life claim remains valid
o Detailed definitions of the specific attributes to be tested at each station (time point), as part of a program that encompasses each quality attribute that may change over the product shelf life
o All procedures that describe these and other elements of your remediated stability program.
Unapproved New Drug Violations
Based on a review of your product labeling, your syNeo antiperspirant products are drugs under section 201(g)(1) of the FD&C Act, 21 U.S.C. 321(g)(1), because they are intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease, and/or intended to affect the structure or any function of the body. Examples from your product labeling, including the website that provide evidence of the intended uses (as defined in 21 CFR 201.128) of these products as a drug include, but may not be limited to, the following:
syNeo ANTI-PERSPIRANT PUMP SPRAY
“
Drug Facts . . . Use
Reduces underarm perspiration.” [from the syNeo ANTI-PERSPIRANT PUMP SPRAY product label]
“…due to its special combination of
2 active ingredients
and thus provides reliable protection against perspiration.” [from the syNeo ANTI-PERSPIRANT PUMP SPRAY product label]
syNeo ANTI-PERSPIRANT ROLL-ON
“
Drug Facts . . . Use
Reduces underarm perspiration.” [from the syNeo ANTI-PERSPIRANT ROLL-ON product label]
“…due to its special combination of
2 active ingredients
and thus provides reliable protection against perspiration.” [from the syNeo ANTI-PERSPIRANT ROLL-ON product label]
syNeo ANTI-PERSPIRANT WET WIPES
“
Drug Facts . . . Use
Reduces underarm perspiration.” [from the syNeo ANTI-PERSPIRANT WET WIPES product label]
“due to its special combination of
2 active ingredients
and thus provides reliable protection against perspiration.” [from the syNeo ANTI-PERSPIRANT WET WIPES product label]
syNeo MAN ANTI-PERSPIRANT PUMP SPRAY
“
Drug Facts . . . Use
Reduces underarm perspiration.” [from the syNeo MAN ANTI-PERSPIRANT PUMP SPRAY product label]
“due to its special combination of
2 active ingredients
and thus provides reliable protection against perspiration.” [from the syNeo MAN ANTI-PERSPIRANT PUMP SPRAY product label]
syNeo MAN ANTI-PERSPIRANT ROLL-ON
“
Drug Facts . . . Use
Reduces underarm perspiration.” [from the syNeo MAN ANTI-PERSPIRANT ROLL-ON product label]
“due to its special combination of
2 active ingredients
and thus provides reliable protection against perspiration.” [from the syNeo MAN ANTI-PERSPIRANT ROLL-ON product label]
syNeo SOFT ANTI-PERSPIRANT PUMP SPRAY
“
Drug Facts . . . Use
Reduces underarm perspiration.” [from the syNeo SOFT ANTI-PERSPIRANT PUMP SPRAY product label]
“due to its special combination of
2 active ingredients
and thus provides reliable protection against perspiration.” [from the syNeo SOFT ANTI-PERSPIRANT PUMP SPRAY product label]
“Aloe vera, panthenol, and allantoin protect your skin from dryness and irritation.” [from the syNeo website at https://syneo.us/]
syNeo SOFT ANTI-PERSPIRANT ROLL-ON
“
Drug Facts . . . Use
Reduces underarm perspiration.” [from the syNeo SOFT ANTI-PERSPIRANT ROLL-ON product label]
“due to its special combination of
2 active ingredients
and thus provides reliable protection against perspiration.” [from the syNeo SOFT ANTI-PERSPIRANT ROLL-ON product label]
“Aloe vera, panthenol, and allantoin protect your skin from dryness and irritation.” [from the syNeo website at https://syneo.us/]
Based on the above labeling evidence, your syNeo antiperspirant products are intended for use as antiperspirant drug products. As described below, these drug products are unapproved new drugs marketed in violation of sections 505(a) and 301(d) of the FD&C Act, 21 U.S.C 355(a) and 331(d).
A drug product is a “new drug” within the meaning of section 201(p) of the FD&C Act, 21 U.S.C. 321(p), if it is not generally recognized as safe and effective (GRASE) for use under the conditions prescribed, recommended, or suggested in its labeling. With certain exceptions not applicable here, a new drug may not be introduced or delivered for introduction into interstate commerce without an approved application from FDA in effect, as described in section 505(a) of the FD&C Act, 21 U.S.C. 355(a). No FDA-approved applications pursuant to section 505 of the FD&C Act, 21 U.S.C. 355, are in effect for these drug products identified above.
Under section 505G of the FD&C Act, certain nonprescription drugs marketed without an approved application —commonly referred to as "OTC monograph drugs"—may be legally marketed if they meet applicable requirements. With respect to nonprescription antiperspirant drug products, such as your syNeo antiperspirant products, in order to be GRASE and not new drugs, the products must, among other things, conform to the conditions in the applicable OTC monograph, here Over-the-Counter Monograph M019: Antiperspirant Drug Products for Over-the-Counter Human Use (hereinafter “M019”).
1
However, the syNeo antiperspirant products do not conform to the conditions specified in M019 for the reasons described below.
2
As formulated, your syNeo antiperspirant products do not conform to the conditions of use set forth in M019. Specifically, your antiperspirant products are labeled to contain aluminum chlorohydrate 10%, and aluminum chloride 10%, as active ingredients. While each active ingredient is individually permitted by M019.10, these active ingredients are not permitted when used in this combination (or any other combination) in a single antiperspirant drug product.
Thus, your syNeo antiperspirant products do not comply with the applicable conditions specified in M019 and have not otherwise been found GRASE.
3
Accordingly, these products are new drugs within the meaning of section 201(p) of the FD&C Act, 21 U.S.C. 321(p), and there is no basis under section 505G of the FD&C Act under which these products would be legally marketed without an approved application. Because there are no applications in effect for these products, these products are unapproved new drugs.
The introduction or delivery for introduction of these unapproved new drug products into interstate commerce violates sections 505(a) and 301(d) of the FD&C Act, 21 U.S.C. 355(a) and 331(d).
Misbranded Drug Violations
Additionally, your syNeo antiperspirant products are misbranded under section 502(ee) of the FD&C Act, 21 U.S.C. 352(ee), because these products are nonprescription drugs subject to section 505G of the FD&C Act, 21 U.S.C. 355h, but do not comply with the requirements for marketing under that section and are not the subject of an application approved under section 505 of the FD&C Act, 21 U.S.C. 355.
The introduction or delivery for introduction of a misbranded drug into interstate commerce violates section 301(a) of the FD&C Act, 21 U.S.C. 331(a).
Consultant
Based on the nature of the violations we identified at your firm, you should engage a consultant qualified as set forth in 21 CFR 211.34 to assist your firm in meeting CGMP requirements.
Your use of a consultant does not relieve your firm’s obligation to comply with CGMP. Your firm’s executive management remains responsible for resolving all deficiencies and systemic flaws to ensure ongoing CGMP compliance.
Quality Systems
Your firm’s quality systems are inadequate. For help implementing quality systems and risk management approaches to meet the requirements of CGMP regulations 21 CFR, parts 210 and 211, see FDA’s guidance documents
Quality Systems Approach to Pharmaceutical CGMP Regulations
at https://www.fda.gov/media/71023/download;
Q9(R1) Quality Risk Management
at https://www.fda.gov/media/167721/download; and
Q10 Pharmaceutical Quality System
at https://www.fda.gov/media/71553/download.
Conclusion
You are responsible for investigating and determining the root causes of any violations and implementing corrective and preventative measures to ensure future and sustained compliance so that these violations and any others do not occur.
FDA may withhold approval of new applications or supplements listing your firm as a drug manufacturer until any violations are completely addressed and we confirm your compliance with CGMP. We may inspect your facility to verify that you have completed corrective actions to any violations.
Failure to address any violations may also result in the FDA refusing admission of articles manufactured at Thomas Brunner Hygiene GmbH, Albershausen, Germany, into the United States under section 801(a)(3) of the FD&C Act, 21 U.S.C. 381(a)(3). Articles under this authority that appear to be adulterated or misbranded may be detained or refused admission, in that the methods and controls used in their manufacture do not appear to conform to CGMP within the meaning of section 501(a)(2)(B) of the FD&C Act, 21 U.S.C. 351(a)(2)(B), and are misbranded under section 502 of the FD&C Act, respectively.
Send your written response to CDER-OC-OMQ Communications@fda.hhs.gov within fifteen (15) business days of receipt of this letter. Identify your written response with FEI 3035784232 and ATTN: Matthew Jensen in the letter or in the subject line of the email.
If you have information that you believe demonstrates that your products are not in violation of the FD&C Act and FDA regulations, include that information for our consideration.
Please note that FDA posts Warning Letters on www.FDA.gov.
Sincerely,
/S/
Francis Godwin
Director
Office of Manufacturing Quality
Office of Compliance
Center for Drug Evaluation and Research
U.S. Food and Drug Administration
/S/
Tina Smith
Captain, U.S. Public Health Service
Director
Office of Unapproved Drugs & Labeling Compliance
Office of Compliance
Center for Drug Evaluation and Research
U.S. Food and Drug Administration
Cc:
(b)(4)
______________________
1
M019 reflects the conditions set forth in the relevant final order established and in effect under section 505G; see Order ID OTC000015, available at FDA’s website OTC Monographs @ FDA, https://www.accessdata.fda.gov/scripts/cder/omuf/.
2
Additionally, your “syNeo SOFT ANTI-PERSPIRANT PUMP SPRAY” and “syNeo SOFT ANTI-PERSPIRANT ROLL-ON” products are intended for use as skin protectant drug products because they “protect your skin from dryness and irritation.” Therefore, these products must also conform to the Over-the-Counter Monograph M016: Skin Protectant Drug Products for Over-the-Counter Human Use (hereinafter “M016”). However, neither M019 nor M016 permits such combination of an antiperspirant with skin protectant drug product. Thus, these products do not comply with the conditions in M019 and M016.
3
FDA is not aware of any adequate and well-controlled clinical trials in the published literature that support a determination that “syNeo ANTI-PERSPIRANT PUMP SPRAY,” “syNeo ANTI-PERSPIRANT ROLL-ON,” “syNeo ANTI-PERSPIRANT WET WIPES,” “syNeo MAN ANTI-PERSPIRANT PUMP SPRAY,” “syNeo MAN ANTI-PERSPIRANT ROLL-ON,” “syNeo SOFT ANTI-PERSPIRANT PUMP SPRAY,” and “syNeo SOFT ANTI-PERSPIRANT ROLL-ON” are GRASE for use under the conditions prescribed, recommended, or suggested in their labeling, nor has FDA determined these drug products to be GRASE pursuant to an order issued under section 505G(b).
Content current as of:
08/04/2026
Regulated Product(s)
Drugs
Over-the-Counter Drugs