Formulation and processing factors influencing the adhesion of film coats to tablet cores

The effect of six factors: spray gun, formulation, inlet temperature, atomizing air pressure, fan air pressure, and gun-bed distance, on the final adhesion of the film coat to the tablet core were assessed. The method used was based on an experimental design, Resolution IV, that allowed the main effects to be free from any two factor interactions. Using a specially designed adhesion tester, values for the maximum force of adhesion, elongation, and area under the curve were obtained. The results obtained show that the effect of all the process parameters on the three adhesive responses measured vary according to which adhesive property is considered. An increase in the fan air pressure decreased the elongation, and increased the area under the curve while the maximum force of adhesion remained unchanged. Both atomizing air and inlet temperature affect the adhesive responses, but they are dependent on the formulation and spray gun used. The gun-bed distance has no influence on the adhesion for the distances used in this study.