SOLID BRIDGE FORMATION IN SULFONAMIDE-EMDEX INTERACTIVE SYSTEMS

Solid bridge formation in model sulphathiazole and succinylsulphathiaz ole-Emdex(R) interactive systems was studied. Changes in adhesion duri ng fluidized column drying were attributed to solid bridge formation c aused by the deposition of dissolved material between the adhered sulp honamide 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 a t a moisture content of 10.5%. The capillary interaction which occurre d in the moist mixtures and preceded the solid bridge formation was ge nerally stronger than the adhesion due to solid bridging. Consideratio n of the adhesion profile changes and interactive behaviour during sto rage provided indirect evidence of solid bridge formation. Both capill ary interaction and solid bridging were influenced by the particle siz e of the drug with the smallest particles being most strongly adhered.