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# End-of-December Warning Letters
- URL: https://www.fdaweb.com/end-of-december-warning-letters/
- Published: 2026-01-06T12:00:00.000Z
- Updated: 2026-09-14T15:29:49.000Z
- Author: David McFarland
- Tags: FDA Policy/General, #legacy-id-D5160426

These are the most substantive Warning Letters FDA issued in the last two weeks of December 2025.

**Darmerica**. A 3/3-3/19/2025 FDA inspection at the Darmerica drug manufacturing facility in Davie, FL, found significant violations, including deviations from current good manufacturing practice (CGMP) for active pharmaceutical ingredients (APIs). A 12/8/2025 [Warning Letter](https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/darmerica-llc-716152-12082025?ref=fdaweb.com) says the company has distributed adulterated or misbranded drugs. The letter cites as a specific deviation the failure of the Darmerica quality unit to exercise its responsibility to ensure that APIs manufactured at its facility comply with CGMP. It lists examples of the deviations and examples of actions that cause the company’s drugs to be misbranded.

Under the heading “Other Concerns,” FDA says there are drug suppliers in the company’s supply chain with a history of non-compliance. It also says its investigators observed the firm destroying original labels during API receipt, inappropriately relying on the results of quality testing of pre-shipment samples that were shipped directly from the API manufacturer to Darmerica’s third-party laboratory for testing, and attempting to import unregistered drugs into the U.S.

Darmerica was told to respond with a list of specific actions it has taken to address the deviations and prevent their recurrence, with a schedule for completing the corrections.

**Devalingam Mahalingam**. An FDA inspection at the clinical site operated by Devalingham Mahalingam in Chicago, IL, found “objectionable conditions” in two clinical investigations he conducted. A 12/11/2025 [Warning Letter](https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/devalingam-mahalingam-md-phd-721145-12112025?ref=fdaweb.com) says that Mahalingam failed to ensure that the investigations were conducted according to the investigational plan.

The letter acknowledged his response to the form FDA-483 and the corrective and preventive actions he had taken, but said the written response was inadequate because it failed to provide specific details on how Mahalingam, as the clinical investigator, would ensure adequate oversight of study procedures and prevent similar violations from occurring in the future.

Mahalingam was told to respond with a list of actions he has taken to prevent similar violations in the future.

**Guangdong Renhe Guozhuang Biotechnology Co., Ltd.** An FDA review of records submitted by Guangdong Renhe Guozhuang Biotechnology Co., Ltd., an over-the-counter drug manufacturer in Guangzhou Guangdong, China, at the request of FDA, identified significant violations of current good manufacturing practice (CGMP) regulations for finished drugs. A 12/16/2025 [Warning Letter](https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/guangdong-renhe-guozhuang-biotechnology-co-ltd-719045-12162025?ref=fdaweb.com) says the specific violations were:

- failure 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, before release, and failure to conduct, for each batch of drug product, appropriate laboratory testing, as necessary, required to be free of objectionable microorganisms;
- failure to conduct at least one test to verify the identity of each component of a drug product; and
- failure to establish adequate written procedures for production and process control designed to assure that manufactured drug products have the identity, strength, quality, and purity they purport or are represented to possess.

The letter says the company’s quality systems are inadequate. FDA recommends that the firm retain a qualified consultant to evaluate its operations and assist it in meeting CGMP requirements.

FDA placed the company’s drugs offered for import on an 11/12/2025 Import Alert.

Guangdong was told to correct the violations promptly and to respond with a list of specific actions it has taken to address the violations and prevent their recurrence, with a schedule for completing the corrections.

**Palamur Biosciences Private Limited**. A bioresearch monitoring inspection at Palamur’s facility in Mahabubnagar, Telangana, India, found objectionable conditions in the firm’s conduct of 14 non-clinical studies. A 12/11/2025 [Warning Letter](https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/palamur-biosciences-private-limited-708579-12112025?ref=fdaweb.com) says the nonclinical studies were used for the development of medical devices. FDA says it found serious violations of Good Laboratory Practice for Nonclinical Laboratory Studies. It cited these violations:

- failure of the study director to assure that all experimental data, including observations of anticipated responses of the test system, are accurately recorded and verified;
- failure of the testing facility to have standard operating procedures in writing setting forth nonclinical laboratory study methods that management is satisfied are adequate to ensure the quality and integrity of the data generated in the course of a study;
- failure of the testing facility management to assure that personnel clearly understand the functions they are to perform; and
- failure of the quality assurance unit to determine that no deviations from approved protocols or standard operating procedures were made without proper authorization and documentation.

Palamur was told to respond with a list of specific actions it has taken to address the violations and prevent their recurrence, with a schedule for completing the corrections.

**Dr. Maria Caballosa**. An FDA bioresearch monitoring inspection at Power MD Clinical Research Institute in Hialeah, FL, found objectionable conditions in her conduct of a clinical trial for an investigational drug. A 12/12/2025 [Warning Letter](https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/maria-carballosa-md-720805-12122025?ref=fdaweb.com) says the agency found that Caballosa failed to retain records required to be maintained for two years following the date a marketing application is approved for the drug for the indication for which it was being investigated or for two years after an investigation is discontinued. The letter says her response to the inspection observation was inadequate. She was told to respond with a list of specific actions she has taken to prevent similar violations in the future.