FDA WARNING_LETTER - Sato Pharmaceutical Co., Ltd. - November 21, 2025

On May 18, 2026, the FDA issued a warning letter to Sato Pharmaceutical Co., Ltd. following an inspection of its manufacturing facility in Tokyo, Japan, conducted from November 13 to 21, 2025. The inspection identified significant violations of Current Good Manufacturing Practice (CGMP) regulations, as defined under the Federal Food, Drug, and Cosmetic Act. These failures led the FDA to classify the company’s over-the-counter drug products as adulterated.

The primary violations involved fundamentally flawed aseptic processing designs in the sterile filling line, which failed to ensure proper airflow and resulted in multiple failed validation attempts. Additionally, the company’s stability program was found deficient, specifically failing to identify or monitor impurity peaks during testing and omitting critical quality attributes like viscosity and degradation. Furthermore, the firm failed to conduct required microbiological testing for opportunistic pathogens, such as Burkholderia cepacia complex, in their water-based products.

Sato Pharmaceutical has voluntarily halted production for the U.S. market. To resolve these issues, the FDA requires a comprehensive independent risk assessment of all contamination hazards, a detailed remediation plan for sterile operations, and retrospective testing of distributed product samples. The company is also advised to hire a qualified consultant to perform a full audit of its quality systems. Failure to correct these systemic flaws may result in the FDA withholding product approvals or refusing the entry of manufactured drugs into the United States.