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2. United States Food and Drug Administration. Draft Guidance for Industry: Metered Dose Inhaler (MDI) and Dry Powder Inhaler (DPI) Products - Quality Considerations. Silver Spring, MD Revised April 2018.
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4. United States Pharmacopeial Convention. Aerosols, nasal sprays, metered-dose inhalers and dry powder inhalers. United States Pharmacopeia 42/National Formulary 37, Chapter 601. Rockville, MD 2018.
5. European Directorate for Quality in Medicines and Healthcare. Preparations for inhalation: aerodynamic assessment of fine particles. European Pharmacopeia 10.0, Chapter 2.9.18. Strasbourg, FR 2019.