Difference in resistance to humidity between commonly used dry powder inhalers

Abstract

Rationale: Multidose Dry Powder Inhalers (DPIs) are common in asthma and COPD treatment. An inherent disadvantage of DPIs is sensitivity to humidity. In real-life, DPIs are periodically exposed to humid conditions, which may affect aerosol characteristics and lung deposition. The present study compared DPI aerosol performance after exposure to humidity. Methods: Budesonide DPIs (200 µg/dose, 200 doses [Pulmicort Turbuhaler; Novopulmon Novolizer; Giona Easyhaler]) were stored in humid conditions (ambient temperature [21°C]; 75% relative humidity) for 3 months. Budesonide delivered (DD) and fine particle dose (FPD) were tested in vitro pre- and post-storage by liquid chromatography at the airflow rate obtained at 4 kPa pressure drop. A decrease > 20% in DD and FPD in vitro was defined as clinically relevant. Results: Both DD and FPD were virtually unchanged after 3 month9s storage for Pulmicort Turbuhaler and Novopulmon Novolizer. For Giona Easyhaler these decreased by 10% and 43% respectively, a decrease that was observed already after 6 weeks storage. Delivered and fine particle dose NT=Not tested Conclusions: This study identified a clinically relevant difference in humidity resistance. After storage, Giona Easyhaler showed a decrease in both DD and FPD in contrast to the other two DPIs. Impaired inhalation aerosol performance may lead to decreased drug delivery to the lungs, affecting clinical outcomes and safety. Sponsor: AstraZeneca.