Layered double hydroxide LDH, obtained by co-precipitation-microwave crysatllization process, had been used as precursors to intercalate a model drug, antipyretic agent acetylsalicylic acid (ASP) to prepare a modified release formulation via difference reaction patterns. The load capacity and drug release process in phosphates had been investigated via analysis both liquid phase and solid phase samples taken early or late respectively from intercalation and release reaction system. The result showed that the interlayer region of LDH was the structural basis for this laminar compound to load, shield and controlled release drugs; the load efficiency influenced by carrier style (mole ratio of LDH), drug proportion, reaction pattern and power of agitator. The characteristic parameter of this complex substance LDH-ASP reflected finely its load efficiency and correlated definitely with its release property. Both intercalation and release of drug caused alteration of lattice parameters and degradation of crystallinity. The crystalline property, thermodynamic change, and specific surface property of LDH-ASP was similar to precursor LDH. However, the offload product LDH-phosphate compared with LDH-ASP and LDH, crystalline state property weaken, amorphous property intensified, interlayer adsorbability reduced, these all would be easy for off-carrier catabolism.

Key words: LDH, loading drug system, crystallinity, load efficiency, drug release