Studies On Synthesis And Controlled Release Of Layered Double Hydroxides Intercalated With Drug

Five pharmaceutically active molecular- Ketoprofenb acid(KA),Loxoprofen acid(LA),Nicotine acid(NA),Sulfanilc acid(SA)and Ferulic acid(FA)in their anionic forms, have been intercalated into the interlayer space of Zn2Al-LDH by the method of co-precipitation. Materials characterization were carried out using XRD, FT-IR, UV-Vis and TG-DTA. The supramolecular structure, thermal behavior and relations between structure and release properties of these organic active agent-intercalated LDHs have been studied.The results indicated that synthetic products had well layered brucite-like structure in control of the experimental condition (Zn/Al=2.0, pH≈9.0, Aging Temperature=70℃, Aging Time=24h). Results suggested that the intercalated organic pharmaceutically active ions still maintained their original structures in the interlayer. The orientation and arrangement of the organic anions within the interlayer of the LDHs had also been investigated. TG-DTA analysis showed that the composite materials had well thermal stability.Layered Double Hydroxides intercalated with drug have good controlled release. Anions in laryers have two kinds of mechanism, one of the ion-exchange is passivie, where the interbedded anions exchange directly with anions in medium. The speed and degree are controlled by concentration,charge and action with laryers of anions in medium. The other is active ion-exchange, in acidic solution, the anions in laryers are protonated and released to the medium solution. Driving force in active ion-exchange is stronger and faster.The study of release with Zn2Al-LDH/COO- indicated the active ion-exchange is main in acidic solution; and that in basic/neutral solution, the passivie ion-exchange is main.The study of release with Zn2Al-LDH/SO3- showed the change of release is small in the acidic or basic medium.