The effect of particle size and concentration on the adhesive characteristics of a model drug-carrier interactive system.

The effect of concentration and particle size on the adhesive tendency of drug particles in a model interactive system was investigated using a centrifuge technique. The model interactive system consisted of drug powders adhered to coated glass carrier beads. Adhesion profiles of per cent of drug remaining on the carrier versus the square of the speed of rotation were a logarithmic normal function. Increase in the adherent particle size and concentration decreased the adhesive tendency of all drug powders studied. Particle collisions during detachment and the formation of multiparticulate layers even before the monolayer saturation of the carrier surface were responsible for the reduced adhesive stability of the drugs on the carrier as the particle loading increased.