THE ADHESION STRENGTH OF PARTICLES OF SALMETEROL BASE AND A SERIES OFSALMETEROL SALTS TO COMPACTED LACTOSE MONOHYDRATE SURFACES

The effect of a systematic change in the chemical structure of salmete rol base, using different salts, on the adhesion force to compacted la ctose monohydrate surfaces, a possible carrier excipient in dry powder aerosols, has been investigated. The chemical structures and the resu lting polarity of the materials have been described using the Hansen-s olubility parameter approach. From the results it is concluded that a prediction of the ranking of the adhesion strength of a series of chem ically related compounds to a defined surface is only partially possib le from a knowledge of the primary chemical structures using the Hanse n-solubility parameter approach. Differences in the molecular configur ation 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 b e predicted from the chemical structure alone, and in any case, the ch oice of a suitable compound for use in a dry powder inhalation can onl y be done on the basis of adhesion experiments.