Scientific and regulatory activities initiated by the U.S. food and drug administration to foster approvals of generic dry powder inhalers: Quality perspective

Regulatory science for generic dry powder inhalation products worldwide has evolved over the last decade. The revised draft guidance Metered Dose Inhaler (MDI) and Dry Powder Inhaler (DPI) Products - Quality Considerations [1] (Revision 1, April 2018) that FDA issued summarizes product considerations and potential critical quality attributes (CQAs). This guidance emphasizes the need to apply the principles of quality by design (QbD) and elements of pharmaceutical development discussed in the International Conference for Harmonisation of (ICH) guidelines. Research studies related to quality were used to support guidance recommendations, which preceded the first approval of a generic DPI product in the U.S. This review outlines scientific and regulatory hurdles that need to be surmounted to successfully bring a generic DPI to the market. The goal of this review focuses on relevant issues and various challenges pertaining to CMC topics of the generic DPI quality attributes. Furthermore, this review provides recommendations to abbreviated new drug application (ANDA) applicants to expedite generic approvals.