Uptake/release of vancomycin on/from Mg-Al layered double hydroxides

For several decades antimicrobial resistance has been a growing threat to the effective treatment of infections, so it is necessary to focus on a rational and effective use of the antibiotics already available. The development of new materials for controlled release of drug is a topic of high priority. Vancomycin (VAN) is a glycopeptide antibiotic used to treat infections caused by gram positive bacteria, and layered double hydroxides (LDH) are inorganic and biocompatible excipients that can provided a long drug release time. In this work, LDH-VAN complexes were synthesized by two methods: co-precipitation and reconstruction. They were characterized by XRD, FTIR, TG, DSC, SEM and EDS, together with dissolution and release kinetics, and electrophoretic mobilities. The coprecipitation samples resulted in particles with a homogeneous chemical composition where there is a rather intimate contact between VAN and the solid phase of the LDH. Reconstruction samples were heterogeneous, but presented higher drug content. There was a congruent dissolution of coprecipitation samples, with VAN being released at the same rate than Mg. Reconstruction samples, on the contrary, dissolved incongruently, with VAN being released much more rapidly than Mg. The rate of VAN release can be tuned and controlled in coprecipitated samples by simply controlling the solution pH.