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Point of view: Inconsistency, confusion and lack of consensus due to the USP Chapter <601> update on nasal delivered dose uniformity (DDU) testing

  • Publication Date: 06/01/2025
  • Author(s):
    Thurston, Grant
  • Organization(s):
    Proveris Scientific Corporation
  • Article Type: Technical Articles
  • Subjects: Industry Issues and Trends, Nasal Delivery, Particle Characterization, Product Development/Formulation, Testing, Validation, and Regulatory Compliance

In 2022, an update to the United States Pharmacopeia (USP) General Chapter <601> Inhalation and Nasal Drug Products: Aerosols, Sprays, and Powders—Performance Quality Tests introduced changes to the sampling procedures for Delivered Dose Uniformity (DDU) testing of nasal spray and nasal aerosol products. These revisions recommend the use of Dosage Unit Sampling Apparatus (DUSA) tubes for nasal spray testing.

The recommendations have caused concern due in part to the additional testing burden needed. Furthermore, the change lacks clinical relevance and does not enhance accuracy and precision in DDU determinations. It has also created confusion, as it is not reflected in the USP monographs and product-specific guidances that the industry follows in product development. This article reviews the roles of the USP, the FDA and IPAC-RS in shaping the regulatory framework for orally inhaled and nasal drug products (OINDPs) and examines the implications of these recent changes to USP <601>. A case study highlights key issues.

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