The impact of addition of force control agent in adhesive mixtures : Effect of magnesium stearates on flowability and aerosolization properties

Abstract: When drugs need to be delivered to the respiratory system dry powder inhalers (DPIs) are often used. The powders in DPIs often consists of a micronized active pharmaceutical ingredient (API) that is adhered to a larger carrier particle forming an adhesive mixture. To achieve a good drug delivery aerosolization is very important and to improve the aerosolization a force control agent such as magnesium stearate (MgSt) may be used. The aim of this project is to investigate how MgSt effects the aerosolization and bulk properties of adhesive mixtures containing different amount of API. Several analyses of bulk properties such as density, bulk density and compressibility were made. The results from these experiments showed that the only bulk properties that had a significant change when MgSt was added was the bulk density. When investigating if the aerosolization properties changed with added MgSt a fast-screening impactor (FSI) and a next generation impactor (NGI) were used. The results showed a clear improvement of aerosolization properties for all the powder containing MgSt. The fine particle fraction (FPF) and fine particle dose (FPD) both increased for all the powder when MgSt was added. The pressure drop sensitivity decreased when MgSt was added which also was desired. In conclusion adding MgSt seems to be beneficial for the aerosolization properties regardless of the amount of API in the powder.