Intercalation and release of antiinflammatory drug diclofenac into nanosized ZnAl hydrotalcite-like compound

A nanostructured hydrotalcite-like compound of formula [Zn0.72Al0.28(OH)2] Br0.28·0.69 H2O has been used as inorganic layered host of the anionic form of diclofenac (DIK), a Non Steroidal Antiinflammatory Drug. The obtained intercalation compound has been characterized by chemical analysis, X-ray powder diffraction pattern, thermogravimetrical analysis and SEM and TEM microscopy. The nanohybrid ZnAl-DIK, with empirical formula [Zn0.72Al0.28(OH)2]DIK0.281.35 H2O and interlayer spacing 22.5 Å, was made up of submicrometric hexagonal platelets. The drug loading was 41.8% w/w. The material was submitted to in vitro drug release studies using three different simulated intestinal media. The release profiles were fitted by mathematical models describing various kinetics in order to investigate the drug release mechanism. The results were compared to literature data obtained with micro-sized MgAl-DIK.

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► Diclofenac has been intercalated into a nanostructured ZnAl-HTlc.
► ZnAl-DIK was submitted to in vitro drug release studies.
► Drug release was complete at pH 7.5 and incomplete in different media at pH 7.0.
► The diffusion of DIK through nanosized ZnAl is faster than that through micro-HTlc.