Direct control of drug release behavior from layered double hydroxides through particle interactions

We report the control of drug release rate from Mg₂Al-layered double hydroxides (Mg₂Al-LDHs) intercalated with ibuprofen as a model drug. Different aggregation states in the dry powders of ibuprofen intercalated Mg₂Al-LDHs can be obtained due to different particle interactions by changing the materials synthesis parameters including the solvent system and aging conditions. Compared with the samples prepared in water alone or aged at atmospheric conditions (70°C, 3 days), the sample synthesized in the mixture of ethylene glycol and water (volume ratio of 1:1) and aged hydrothermally (150°C, 18 h) exhibits a more stable suspension of regularly shaped and larger LDH platelets (ca. 450 nm). Upon drying, it forms relatively oriented dense powder through preferential face-to-face and edge-to-edge aggregation. The release rate of ibuprofen from such dense powder is considerably lower compared with those from the loose powders. This can be attributed to a less breakdown of aggregates, a longer diffusion path length and a higher diffusion resistance in the oriented solid matrix.