UCL Discovery

Abstract

The effect of a systematic change in the chemical structure of salmeterol base, using different salts, on the adhesion force to compacted lactose monohydrate surfaces, a possible carrier excipient in dry powder aerosols, has been investigated. The chemical structures and the resulting polarity of the materials have been described using the Hansen-solubility parameter approach. From the results it is concluded that a prediction of the ranking of the adhesion strength of a series of chemically related compounds to a defined surface is only partially possible from a knowledge of the primary chemical structures using the Hansen-solubility parameter approach. Differences in the molecular configuration and differences in the surface roughness of the powder particles adhered are also important considerations. These factors may dominate over the influence of the primary chemical structure. The appropriate deformation characteristics such as ductility or brittleness cannot be predicted from the chemical structure alone, and in any case, the choice of a suitable compound for use in a dry powder inhalation can only be done on the basis of adhesion experiments.