Adhesive mixtures for inhalation: the cohesion between formulation variables, inhalation variables and dispersion performance

Powdery drugs for inhalation to treat asthma and COPD are often mixed with lactose to enable their accurate dosing. However, because the drug particles adhere strongly to the lactose particles, they are difficult to disperse with the aid of a dry powder inhaler. As a result, over half the dose usually does not reach the site in the lungs where it should exert its therapeutic effect. Instead, it may cause adverse reactions in the mouth and throat, such as fungal infections and hoarseness.

To enable the development of so-called adhesive mixtures for inhalation that are better dispersible it was studied at the University of Groningen how variables of the formulation and inhalation process influence powder dispersibility. How, for example, do the drug content and the mixing process affect powder dispersibility? And how do these variables influence each other?

The study showed that the influence of such variables on powder dispersion depends strongly on the choice of other variables. Several mixture properties that are important for explaining this complex cohesion between the variables have been identified and defined. In addition, new methods have been introduced to measure them. The study, therefore, has not only improved the current understanding of adhesive mixtures for inhalation, but it will also improve the efficiency of future research on this subject. This enables the development of adhesive mixtures that are better dispersible, so that asthma and COPD can be treated more effectively and safely by dry powder inhalation.