Evaluation of the Droplet Collapsibility in Inhalation Drug Delivery through a 3D Computational Study

Background: several multiphase flow analyses have been developed to predictthe fate of particles used in inhalation drug delivery; however, the collapse of dropletsduring their passage through respiratory tract has not been investigated.objective: to assess the probability of droplet collapse in the upper respiratorytract.methods: a 3d model of mouth-to-second generation airway after the tracheawas developed with application of a computational fluid dynamics modeling. a newparameter, the droplet collapsibility index (dci), was defined to evaluate the probabilityof droplet collapse during the release of droplets through the model.results: the results stated that droplets with diameter between 0.1 and 1 ?m areat higher risk of collapse. also, the most probable region of collapse was found to bethe glottal bend. the condition becomes progressively worse by increasing the rateof breathing air flow. by increasing the inspiration flow rate from 10 to 30 l/min, thedroplet collapsibility rised from 0.75 to 2.25—exceeding the collapsibility threshold.conclusion: results of the current study can be used in evaluation of collapsibilityof particles in design of inhalation drug delivery systems.