Influence of single versus multiple actuations on the particle size distribution of beclometasone dipropionate metered-dose inhalers

The particle size distributions of beclometasone dipropionate delivered from Becotide and Respocort inhalers after single and multiple actuations were investigated using the Andersen Mark 11 Cascade impactor and the drug was quantified using high performance liquid chromatography. The fine particle mass and the mass median aerodynamic diameter were calculated. An apparent increase in mass median aerodynamic diameter was observed when the number of actuations increased. In addition, the fine particle mass decreased as the number of actuations increased. When performing and analysing cascade impaction study data differences between single versus multiple actuations must be considered. Regulatory guidelines should be amended to stipulate the number of actuations to be loaded into devices used to evaluate the particle size distribution of inhaled aerosol products.