Adhesion force measurement by centrifuge technique as tool for predicting interactive mixture stability.

• Centrifuging/image analysis was developed for particle-surface adhesion study • The effect of surface heterogeneity on particle-surface adhesion was investigated • The distribution of adhesion strength mapped particle behaviour on rugged surfaces • Adhesion strength distribution can determine critical surface coverage An interactive mixture, i.e. a blend of larger carrier particles with drug particles adhered on their surfaces, is often used in pharmaceutical formulations for promoting powder flow, improving blend uniformity, reducing the segregation risk during manipulation, and improving the solubility of poorly water-soluble drug. Obtaining uniform and stable interactive mixtures require adhesion forces between fine drug and coarse carrier particles to exceed the cohesion forces between drug particles. This work was aimed at developing the methodology measuring the particle adhesion by centrifugation combined with the optical microscopy to predict interactions between components in the mixtures. In the pilot phase, excipient particles were chosen as model substances, both for the preparation of the carrier surface and deposited particles. As expected, our developed methodology was able to map the behaviour of particles on the rugged surfaces and provide the adhesion strength distribution used for comparing different material adhesion. It can also provide a measure of interactive unit stability when the mixture undergoes process treatment characterised by certain mechanical stress. [ABSTRACT FROM AUTHOR]