Characteristics and release of gentamicin sulphate from sodium alginate microspheres entrapped in emulgel

Gentamicin sulfate is a broad-spectrum aminoglycoside antibiotic that can be used for primary and secondary infections of the skin. Microspheres can be used to extend drug release on the skin; the resulting therapeutic effect is constant and has a longer duration of action. Therefore it can reduce the frequency of use and increase patient compliance. This study investigated the appropriate profile and release kinetics model of gentamicin sulfate microspheres entrapped on the emulgel base. Gentamicin-alginate microspheres were made by the ionotropic gelation method with aerosolization technique, using 2.5% Na-alginate low viscosity, CaCl₂ solution of 1.5M as a crosslinker, maltodextrin as lyoprotectant and were dried using the freeze-drying method. The result of microspheres characterization, gentamicin microsphere was spherical with smooth surface structure and had particle diameter of 3.021 ± 0.017µm. Gentamicin microspheres had moisture content 2.89%, and maximum swelling index was 2625 ± 21.70% was achieved within 5 hours. The drug loading of microspheres was 1.75 ± 0.11%, and entrapment efficiency was 10.96 ± 0.19%. The release evaluation during 720 minutes showed that the amount of gentamicin release from alginate microspheres on emulgel base was 14.857 ± 0.816%, and gentamicin release on emulgel conventional was 49.239 ± 5.954%. The model of release kinetics of gentamicin microspheres on emulgel was Higuchi model that showed the release of the active ingredient through the diffusion process. While the model of release kinetics of gentamicin on emulgel base was first order, that showed the release of active agent depends on remaining concentration.