SOLID BRIDGE FORMATION IN SULFONAMIDE-EMDEX INTERACTIVE SYSTEMS

Solid bridge formation in model sulphathiazole and succinylsulphathiazole-Emdex(R) interactive systems was studied. Changes in adhesion during fluidized column drying were attributed to solid bridge formation caused by the deposition of dissolved material between the adhered sulphonamide particle and carrier surface reinforcing the interaction. The formation of the solid bridges was dependent on the moisture content of Emdex(R) in the predried mixture with adhesion reaching a maximum at a moisture content of 10.5%. The capillary interaction which occurred in the moist mixtures and preceded the solid bridge formation was generally stronger than the adhesion due to solid bridging. Consideration of the adhesion profile changes and interactive behaviour during storage provided indirect evidence of solid bridge formation. Both capillary interaction and solid bridging were influenced by the particle size of the drug with the smallest particles being most strongly adhered.