Abstract
Dispersion performance of Dry Powder Inhaler (DPI) depends largely upon the inhalation patterns of patients. Slight increase in pressure drop of DPI markedly reduces the peak flow rate of inspired air, however, the dispersion performance of DPI is not significantly affected by the change in DPI flow resistance under the simulated inspiration pattern because the total energy available for the particle dispersion with the DPI is almost the same. Furthermore, Andersen Sampler which is commonly used for the evaluation of dispersion performance of DPI is not suitable for this purpose because the dispersion of drug particles takes place in the sampler with almost the same extent as that of DPI. Therefore, it is important to evaluate the dispersion performance of DPI under the simulated inspiration pattern with the DPI using a particle sizer without particle dispersion in the instrument.
