DELIVERED DOSE UNIFORMITY (DDU)

The IPAC-RS Delivered Dose Uniformity (DDU) Working Group addressed issues with DDU specifications for orally inhaled and nasal drug products recommended in the FDA draft guidances of 1998-1999. At the outset, the Working Group collected and analyzed industry data, summarized in the initial assessment report submitted to the Agency in 2000. Subsequently, IPAC-RS developed a parametric tolerance interval test for DDU, submitted to FDA in 2001. (An updated SAS code was made available in September 2002).

In early 2003, the Agency indicated that the approach proposed by IPAC-RS was acceptable in principle, but several technical questions needed clarification. The ACPS considered the details of the IPAC-RS proposal on 13 March 2003 and continued the discussion on 21 October 2003.

The DDU specifications (i.e., test and acceptance criteria) proposed by IPAC-RS reflected the consumer protection implied by FDA draft guidances, were in line with FDA regulatory practice as well as non-FDA public standards, and took into account manufacturing and analytical capabilities of existing and developing inhalation technologies. The problems that led the industry to the development of these specifications were highlighted in the IPAC-RS DDU Working Group's presentation at the ninth international symposium Respiratory Drug Delivery in 2004. Another presentation at that conference used the example of DDU specification setting to illustrate important risk management concepts.