The aim of the present work is to identify and understand the complex relationship between powder properties and the capsule filling performance of a dosator nozzle machine. Twelve different powders, mainly inhalation carriers and selected APIs, were characterized and filled into size 3 capsules following a screening DoE for different process parameters. Subsequent multivariate statistical analysis was used to identify the influence of various powder properties and process parameters on the capsule net weight and weight variability. There was a clear correlation between the dosator filling performance the dosator diameter, dosing chamber, powder layer and the powder densities. Moreover, wall friction angle and basic flowability energy are also significant parameters. The results were used to develop a predictive model for the process and furthermore a design space for the different nozzles and powders.
The results of the work will translate into guidelines for improving the current design of capsule filling equipment, for particle engineering and ultimately will allow the manufacturing of inhalation products with desired quality attributes. This study is the first scientific qualification of dosator nozzles for low fill weight (5-45 mg) capsule filling.