kdc/one Chatsworth, Inc. MARCS-CMS 733205 — September 08, 2026

WARNING LETTER

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• Delivery Method: VIA ELECTRONIC MAIL READ/DELIVERY RECEIPT
• Reference #: 320-26-124
• Product: Drugs ; Over-the-Counter Drugs

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• Recipient: Mr. Peter F. Rawson; Vice President and General Manager ; kdc/one Chatsworth, Inc.; 20320 Prairie St.; Chatsworth, CA 91311-6026; United States; prawson@kdc-one.com

• Issuing Office: Center for Drug Evaluation and Research (CDER); United States

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September 8, 2026

WARNING LETTER
Reference number: 320-26-124

To Mr. Peter F. Rawson:

This warning letter advises you of significant violations observed during a U.S. Food and Drug Administration (FDA) inspection of your facility. Promptly address the violations described herein without delay, including ensuring that appropriate resources are allocated to fully address the violations and prevent their recurrence. This is not intended to be an all-inclusive list of the violations that exist at your facility. It is your responsibility to ensure that your firm complies with all requirements of federal law, including FDA regulations. Failure to adequately address violations may result in regulatory action without further notice including, without limitation, seizure and injunction.

Violations were observed and documented during an inspection of your drug manufacturing facility, kdc/one Chatsworth, Inc., FDA Establishment Identifier (FEI) 1000519695, at 20320 Prairie St., Chatsworth, CA, from March 31 to April 3, 2026. This inspection was conducted under FDA’s statutory authority and public health responsibilities to protect the public from unsafe, ineffective, and poor quality drugs.

This warning letter summarizes significant violations of Current Good Manufacturing Practice (CGMP) regulations for finished pharmaceuticals. See Title 21 Code of Federal Regulations (CFR), parts 210 and 211 (21 CFR parts 210 and 211).

Because your methods, facilities, or controls for manufacturing, processing, packing, or holding do not conform to CGMP, your drug products are adulterated within the meaning of section 501(a)(2)(B) of the Federal Food, Drug, and Cosmetic Act (FD&C Act), 21 U.S.C. 351(a)(2)(B).

We reviewed your April 24, 2026, response to our Form FDA 483 in detail.

Violations of the Federal Food, Drug, and Cosmetic Act

The following are violations identified during our inspection and 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. Your firm also failed to establish and follow an adequate written stability testing program that included reliable, meaningful, and specific test methods for assessing the stability characteristics of these drug products (21 CFR 211.165(a) and 211.166(a)).

Your firm manufactures various (b)(4) over-the-counter (OTC) drug products, including those containing the active ingredient (b)(4) and the inactive ingredient (b)(4). You failed to establish scientifically sound and appropriate finished product specifications. For example, you did not include (b)(4) testing as a release or stability requirement.

Under certain conditions, (b)(4) can degrade through a known mechanism to form (b)(4), a known carcinogen. Also, when (b)(4) is present in a drug formulation in combination with certain chemicals such as (b)(4), it may react under certain conditions to generate (b)(4). Over the drug product's shelf life, (b)(4) can accumulate and increase in concentration. Despite these known degradation and reaction pathways, you distributed at least (b)(4) batch of an OTC (b)(4)-containing drug product into interstate commerce without (b)(4) testing.

Your quality unit is responsible for ensuring that appropriate testing and procedures are in place and followed prior to releasing drug products for distribution.

Your firm’s inadequate response to a known contamination event further compounds these failures. Your firm was aware that your customer voluntarily recalled (b)(4) products in Canada on (b)(4), due to potential (b)(4) contamination. The recalled batches were manufactured at your facility using the same formulation, packaging, and labeling used for products distributed in both the United States and Canada. Despite being notified of (b)(4) contamination in your product, your firm failed to determine whether the recalled batches were also distributed in the United States and did not evaluate the potential risk to U.S. consumers.

During the inspection, your firm confirmed that you do not test OTC drug products that contain (b)(4) or (b)(4) for (b)(4) before release or during stability testing. Your written risk assessments for (b)(4) contamination are inadequate.

In your response, you commit to discontinue your manufacturing of (b)(4) and (b)(4) and to deactivate the drug listing for (b)(4) and (b)(4). You also commit to engaging a third-party laboratory for (b)(4) testing, updating release and stability specifications, and completing comprehensive risk assessments for all currently marketed OTC drug products.

Your response is inadequate. You did not provide test results to show products still in the market are below the recommended (b)(4) levels. Most critically, your firm failed to evaluate the impact of (b)(4) contamination identified in (b)(4), which was recalled in other markets. You also failed to identify other potentially affected batches or conduct appropriate market action assessments. Further, your response does not demonstrate that your third-party laboratory is qualified to perform (b)(4) testing on your drug products.

FDA has alerted drug manufacturers of products at risk for presence of (b)(4) that they should be testing those drug products for (b)(4). For more information see (b)(4).

In response to this letter, provide:

• A list of chemical and microbial specifications, including test methods, used to analyze each lot of your drug product before a batch disposition decision.
• A detailed description of the method you establish to test for (b)(4) in finished products prior to release.
• An action plan and timelines for conducting full chemical and microbiological testing of retain 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 retain samples from each lot of (b)(4) products and (b)(4) products that are currently on the U.S. market within expiry. If retain samples of component lots are unavailable, perform retain sample testing of all implicated finished drug product batches for the presence of (b)(4). If testing reveals substandard-quality drug products, take rapid corrective actions, such as notifying customers and initiating product recalls. Provide your market action plan to ensure that no batches potentially contaminated with (b)(4) remain in the U.S. market.
• 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.
• A comprehensive assessment and corrective action and preventive action (CAPA) plan to ensure the adequacy of your stability program. Your remediated program should include, but not be limited to, the following:
  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 whether the shelf-life claim remains valid
  o Detailed definition of the specific attributes to be tested at each station (timepoint), as part of a program that encompasses each quality attribute that may change over the product shelf-life
• All procedures that describe these and other elements of your remediated stability program.

2. Your firm failed to thoroughly investigate any unexplained discrepancy or failure of a batch or any of its components to meet any of its specifications, whether or not the batch has already been distributed (21 CFR 211.192).

Your firm failed to adequately investigate viscosity failures obtained during stability testing of distributed OTC drug products. Specifically, stability testing records documented (b)(4) out-of-specification (OOS) results without adequate root cause determination, CAPA, or documented justification for the established (b)(4) specifications.

In your response, you attribute the root cause to inadequate documentation of the (b)(4) specification changes and commit to evaluating the adequacy of supporting data, conducting a retrospective review of past OTC stability failures, updating your procedure, and training staff.

Your response is inadequate because you did not include a risk assessment for previously distributed products with viscosity OOS results, a CAPA plan with clear timelines, documented justification for your established (b)(4) specifications, and an updated procedure supported by staff training records.

It is essential to conduct thorough well documented, and scientifically sound investigations to identify root causes of OOS results, evaluate all potentially affected batches, and implement timely and effective CAPA plans. For more information about handling failing, out-of-specification, out-of-trend, or other unexpected results and documentation of your investigations, see FDA’s guidance document Investigating Out-of-Specification (OOS) Test Results for Pharmaceutical Production at https://www.fda.gov/media/158416/download.

In response to this letter, provide:

• 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.
• A retrospective, independent review of all invalidated OOS (including in-process and release/stability testing) results for products currently in the U.S. market and within expiry as of the date of this letter and a report summarizing the findings of the analysis, including the following for each OOS:
  o Determine whether the scientific justification and evidence relating to the invalidated OOS result conclusively or inconclusively demonstrates causative laboratory error.
  o For investigations that conclusively establish laboratory root cause, provide rationale and ensure that all other laboratory methods vulnerable to the same or similar root cause are identified for remediation.
  o For all OOS results found by the retrospective review to have an inconclusive or no root cause identified in the laboratory, include a thorough review of production (e.g., batch manufacturing records, adequacy of the manufacturing steps, suitability of equipment/facilities, variability of raw materials, process capability, deviation history, complaint history, batch failure history). Provide a summary of potential manufacturing root causes for each investigation and any manufacturing operation improvements.
• A comprehensive assessment and remediation plan to ensure your quality unit (QU) is given the authority and resources to effectively function. The assessment should also include, but not be limited to, the following:
  o A determination of whether procedures used by your firm are robust and appropriate.
  o Provisions for QU oversight throughout your operations to evaluate adherence to appropriate practices.
  o A complete and final review of each batch and its related information before the QU disposition decision.
  o Oversight and approval of investigations and discharging of all other QU duties to ensure identity, strength, quality, and purity of all products.

3. Your firm failed to store drug products under appropriate conditions of temperature, humidity, and light so that the identity, strength, quality, and purity are not affected (21 CFR 211.142(b)).

Your firm failed to establish and follow adequate temperature monitoring and warehousing procedures for finished drug products. For example, you released (b)(4), batch (b)(4), on (b)(4), and stored it in Building (b)(4), until you shipped it on (b)(4). The product label specifies storage at (b)(4)°C–(b)(4)°C, however, you recorded high temperatures of (b)(4)°C–(b)(4)°C in Building (b)(4) during this storage period. The temperatures in Building (b)(4) exceeded both the labeled storage conditions and your firm's internal temperature monitoring protocol.

A review of Building (b)(4) temperature data from April 2025 through March 2026 identified approximately (b)(4) weeks where temperatures exceeded (b)(4)°C. Exposure to elevated temperatures in (b)(4)-containing products poses a risk of (b)(4) contamination. Furthermore, your firm did not include storage condition requirements on your certificates of analysis (COAs).

In your response, you commit to updating the procedure, revising temperature mapping protocols, conducting a retrospective evaluation of temperature monitoring data across all warehouse areas, and completing relevant personnel training.

Your response is inadequate. You did not implement immediate corrective actions and did not conduct a thorough retrospective review of product impact for temperature excursions, including for the formation of impurities and degradants when products are exposed to heat.

In response to this letter, provide:

• Your procedure for environmental controls and alarm limits for storage areas.
• A list of the different types of drug products and related materials you store in your warehouse (for example, finished drug products, unlabeled drug products, expired drug products, raw materials, and components) and a current inventory, including manufacturer-assigned expiration dates and status (for example, released, quarantined, rejected).
• A risk assessment for batch (b)(4) (vendor lot #(b)(4)) addressing the impact of temperature excursions on product quality, including (b)(4) formation risk.
• A comprehensive retrospective review of temperature monitoring data across all storage and warehouse areas to identify any instances in which OTC drug products were stored outside of their labeled storage conditions. This review should encompass all products and all time periods for which temperature data is available and should result in a documented assessment of any affected lots, including an evaluation of potential impact on product quality, safety, and efficacy.
• A comprehensive review of all OTC finished drug product storage conditions across all buildings, comparing labeled storage requirements against recorded temperature data, with documentation of any corrective actions taken.
• Updated written procedures ensuring storage conditions are included on COAs and shipping labels.

CGMP Consultant Recommended

Based upon 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 Unit Authority

Your inspectional history indicates that your quality unit is not able to fully exercise its authority and/or responsibilities. Your firm must provide the quality unit with the appropriate authority and sufficient resources to carry out its responsibilities and consistently ensure drug quality.

Cosmetics Manufactured for Distribution in the United States

In addition, some of the products you manufacture may be regulated as cosmetics, as defined in section 201(i) of the FD&C Act [21 U.S.C. 321(i)]. Any cosmetics you manufacture must comply with applicable statutory and regulatory requirements, including the FD&C Act. We note that under section 301(a) of the FD&C Act [21 U.S.C. 331(a)], it is a prohibited act to introduce or deliver for introduction into interstate commerce a cosmetic that is adulterated or misbranded.

We also note that the Modernization of Cosmetics Regulation Act of 2022 (MoCRA) provides new requirements with which facilities that manufacture cosmetic products must comply. You may find the FD&C Act, MoCRA, and FDA’s regulations through links on FDA’s website at www.fda.gov.

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.

Unresolved violations may prevent other Federal agencies from awarding contracts. Failure to address violations may also cause FDA to withhold issuance of Export Certificates. 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 re-inspect to verify that you have completed corrective actions to address any violations.

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 1000519695 and ATTN: Chhaya Shetty 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.

FDA posts warning letters to 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