There is an increasing interest in the use of clays of diverse structure (smectites, halloysite nanotubes, layered double hydroxides,...) as substrates for the preparation of drug delivery systems (DDS). One way to achieve better control in the release process is the incorporation of the drug-clay system in biopolymeric matrices, in particular polysaccharides, leading to the development of new pharmaceutical compositions for oral and topical treatments. To show the ability of bionanocomposites as controlled DDS, this communication will present the case leading to the optimization of a bionanocomposite system for the oral administration of metformin. Metformin is the most widely used oral antidiabetic drug for the treatment of type 2 diabetes, being more recently explored for uses in the treatment of certain types of cancer. Oral administration of this drug presents certain problems because the high doses needed to ensure an adequate level of intestinal adsorption can cause various adverse gastrointestinal effects in patients. In this context, our group has carried out a systematic study of the association of metformin with clays of the smectite type (montmorillonite and laponite) to produce reliable DDS for metformin. Metformin can be intercalated and also adsorbed on the external surface of the clay which results. In our studies we have confirmed that the processing of these metformin/clay systems into polysaccharides such as pectin or chitosan allows a controlled release process from the produced bionanocomposites. Moreover, the processing of the bionanocomposites in the form of beads also allows to play with the possibility of procuring additional coatings that stabilize the system at the variable pH environments that will be found along their passage through the gastro-intestinal tract. Thus, it has been possible to optimize a DDS where a clay-metformin/pectin bionanocomposite is coated first with chitosan and then with pectin, allowing the encapsulation of high amount of metformin (around 90%). These core-shell beads are stable at pH as lower as those of the stomach, ensuring that the DDS reaches the adsorption zone in the intestine and prolongs the residence time favored by the mucoadhesive properties of chitosan. This example could be the basis to optimize clay-based bionanocomposite DDS for administration of other oral drugs.

Clay-biopolymer nanocomposites for drug delivery applications: a case to achieve the controlled delivery of metformin

ACS Spring Meeting 2021

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