Reconstitution as an alternative method for 5-aminosalicylic acid intercalation in layered double hydroxide for drug delivery

Among a great variety of applications, layered double hydroxides (LDH) can be used as drug delivery systems improving the dissolution rate of poorly water-soluble drugs. Different methods, as co-precipitation, ion exchange, reconstitution, among others, can be used in order to intercalate drugs in the LDH interlayer space, such as 5-aminosalicylic acid (5ASA), widely used in the treatment of inflammatory bowel diseases, although it presents low bioavailability and water solubility. The chosen method can determine structural and material properties of the final product, such as crystal size, particle distribution and morphology. This study presents the reconstitution method as an alternative. The samples were characterized by elemental analysis, X-ray diffraction, infrared molecular absorption spectroscopy, thermal analysis and atomic force microscopy. The characterization proved the interaction between LDH and 5ASA by changes in the interplanar distances and hydrogen interactions between drug and layer hydroxyls. This system presented a 25.5% of drug load. Also, the microscopy showed a rough surface in the system, indicating that the drug was not only present in the LDH interlayer space, but also adsorbed on its surface. This set of data indicate that the method was efficient for 5ASA intercalation in the LDH, reinforcing the proposal of LDHs as functional pharmaceutical excipients.