Introduction to Delivered Dose Uniformity (DDU)

The Delivered or Emitted Dose is the total amount of drug emitted from the inhaler device and hence available to the user.

Its uniformity is a Critical Quality Attribute (CQA) in determining the safety, quality and efficacy of an orally inhaled and nasal drug product (OINDP).

Based on an original design by Charles Thiel in 3M’s laboratories in Minneapolis, USA, the Dosage Unit Sampling Apparatus (DUSA) for MDIs has been designed specifically for the sampling and testing of Metered Dose Inhalers (MDIs).

It is used to perform those tests specified in the Pharmacopoeias relating to “delivered” or “emitted” dose, namely “Delivered Dose Uniformity” and “Delivered Dose Uniformity over the Entire Contents”.