Investigation of dry powder inhalation aerosolisation performance at different flow rates from a conventional capsule-based inhaler device

Imran Y Saleem, Rajith KR Rajoli, Brian E Jones, Fernando Diez

Background: Generally capsule-based dry powder inhalers (DPIs) are required to be used at a flow rate of 60 L/min to initiate removal and deaggregation of the drug from carrier for effective pulmonary deposition. This may not be appropriate for children or those with lung diseases. In addition, capsule-based DPI are intended for treatment over a 4-week period and storage conditions can influence the aerosolisation drug deposition, reproducibility of inhalation dose and treatment outcome. Methods: Inhalation grade lactose was blended with micronized salbutamol (50:1w/w) and filled (20±1mg) in to size 3 hypromellose inhalation grade capsules stored at 22ºC 40% RH for 4 weeks. Samples were tested using a 2-pin inhaler and aerosolised through a next generation impactor at flow rates of 30 L/min (actuated for 8s) and 60 L/min (actuated for 4s) at weekly intervals for 4 weeks. Deposition of drug in the capsule, device and emitted dose (ED), fine particle dose (FPD), percentage fine particle fraction (FPF) and mass aerodynamic diameter (MMAD) were calculated. Results: Powder retention within capsules was higher at 60 L/min whereas it was higher in the device at 30 L/min (p<0.05/Tukey). The ED, FPD, FPF was significantly greater at 60 L/min compared to 30 L/min at each time point (p<0.05/Tukey). However, there was no significant difference comparing each flow rate over time. Conclusion: Differences in results between the air flow rates at each weekly time points highlight the important relationship between inhalation, therapeutic dose, lung deposition and potential therapeutic outcome.

Join today to view and download the full abstract/presentation