Tribo-Charging Behaviour of Inhalable Mannitol Blendswith Salbutamol Sulphate

Purpose The performance of carrier-based dry powder inhaler(DPI) formulations can be critically impacted by interfacialinteractions driven by tribo-electrification. Therefore, theaim of the present work was to understand how distinct APIparticle characteristics affect the charging behaviour of blendsintended for DPI delivery.Methods Salbutamol sulphate (SBS) particles engineered viaspray-drying and jet milling were used as model APIs. Dmannitolwas selected as a model carrier. The materials werecharacterized concerning their different particle propertiesand their charge was analysed alone and in blends beforeand after flow over a stainless-steel pipe.Results The spray-dried SBS (amorphous and spherical)charged positively and to a higher extent than jet milled SBS(crystalline and acicular) that charged negatively and to a lowerextent. D-mannitol charged positively and to a higher extentthan the APIs. All drug-excipient blends charged negativelyand differences were found between the spray-dried andjet milled SBS blends at 2% and 5% drug loads.Conclusions It was demonstrated how distinct solid-states, particleshape, size and morphology as well as different water contentsof the different materials can affect tribo-charging. For theirbinary blends, the amount and nature of fines seem to governinter-particle contacts critically impacting charge evolution.