Impact of Pre-Actuation Shaking on the Aerosolization Performance of Easyhaler® Salbutamol Dry Powder Inhaler

PURPOSE OR OBJECTIVE: Each Easyhaler^® Salbutamol 100 μg dry powder inhaler (DPI) uniquely requires pre-actuation shaking, unlike most commercial DPIs. This study aimed to investigate the aerodynamic and functional implications of pre-actuation shaking to determine its effect on drug delivery performance.

Device actuation was performed following 0 to 5 pre-actuation shakes. Performance was assessed using a multi-technique approach: cascade impaction, dose uniformity testing (DUSA), laser diffraction (SprayTec), optical microscopy, and scanning electron microscopy (SEM). Key parameters measured included emitted dose (ED), delivered dose (DD), fine particle dose (FPD), fine particle fraction (FPF), mass median aerodynamic diameter (MMAD), and throat deposition.

Delivered dose remained relatively constant regardless of shaking. However, FPD and FPF significantly improved with increased shaking, particularly at three to five shakes. Cascade impaction demonstrated reduced throat deposition and greater deposition in stages 3-4 (< 5 µm respirable fraction) under these conditions. An inverse correlation between throat deposition and FPF was identified. SEM and microscopy confirmed consistent particle morphology and blend uniformity, while laser diffraction showed a predominance of larger carrier particles under 0-shake conditions.

Pre-actuation shaking substantially influences the aerosolization performance of Easyhaler^® Salbutamol. At least three vertical shakes are required to achieve optimal fine particle delivery and reduce throat deposition. These findings highlight the importance of proper patient instruction on device handling. Further studies should assess whether similar effects occur with other Easyhaler^® formulations.