Powder Characterization For DPI Performance In Capsule-Based Inhalers

Respiratory diseases are commonly treated with orally inhaled drugs – via dry powder inhalers (DPIs), for example. DPIs typically consist of the micronised API in the size range 1–5 μm, blended with a larger inactive carrier material. But such small API particles often have poor flowability and high cohesion, which makes handling difficult. Moreover, they rarely exhibit the expected performances in terms of aerosolisation and absorption. Consequently, their properties must be improved with the addition of larger carrier particles to reach the required performance.

Lactose is often used, and the large variety of available grades allows for designing the DPI according to the requirements. However, it remains difficult to predict the behaviour of the blend. The fine particle fraction and the fine particle mass (FPM) are quantities measured via impaction to evaluate the in vitro aerosolisation performance of the API. Since this measurement is cumbersome and time consuming, simple methods to evaluate DPI performance based on bulk powder characterisation are necessary. Therefore, different studies have focused on the investigation of measurement methods for DPI characterisation.

In this study, Granutools and Research Center Pharmaceutical Engineering (RCPE) characterised three powder blends of salbutamol sulphate (SBS) with distinct lactose grades using tapped density (GranuPack, Granutools) and rotating drum (GranuDrum, Granutools) methods. Their usability has been evaluated by correlating the bulk powder properties with the in vitro performance when the mixtures are delivered with a capsule-based inhaler.

Read the Paper here