Prolonged release of metformin by SiO2 nanoparticles pellets for type II diabetes control.

Mesoporous silica nanoparticles (MSNPs) were synthesized and loaded with metformin hydrochloride (Metf), its adsorption has studied at different concentrations and pHs, optimal adsorption conditions were determined. Hybrid MSNPs-Metf were mixed with chitosan to compress them and form quasi-spherical pellets, were coated with five chitosan layers as a barrier to prolong metformin release. It showed that this pellet is useful for metformin controlled release since drug over time was significantly delayed by the chitosan coating and then, as metformin is electrostatically linked to MSNPs, it also controls the release of drug, releasing 170 mg after 17 h of exposure at pH 1.2. When pH is >1.2, metformin release was significantly prolonged. Since 170 mg is 21% of a 850-mg metformin dose and previous studies report that 90% of metformin is recovered as unchanged drug in urine after 12 h of metformin intakes. These results suggest that MSNPs-Metf pellets, coated with chitosan, are an option to avoid excessive metformin ingest.