Preparation of Gentamicin Sulfate Nanoparticles using Eudragit RS-100 and Evaluation of Their Physicochemical Properties

Improving permeability and absorption of drugs are critical research challenges in pharmaceutical science. Gentamicin sulfate is an aminoglycoside antibiotic, which is very active against gram-negative bacteria; however, it has very poor bioavailability. This study aimed to prepare gentamicin nanoparticles with the intention of increased bioavailability. Accordingly, Eudragit RS-100 nanoparticles loaded with gentamicin sulfate were prepared by the double emulsification and solvent evaporation method, a proper technique for encapsulating hydrophilic molecules. Nanoparticles' suspensions with polymer to drug ratios of 1:1 (F-a) and 2:1 (F-b) were prepared, lyophilized and evaluated for their production yield, physicochemical properties and morphology. The mean particle size was 195.67nm and 228nm for F-a and F-b, respectively. The formulations' loading efficiencies were relatively high (85.73 for F-a and 85.20 for F-b). The nanoparticles' surface charge (+40.5mV) was sufficient to inhibit their aggregation and facilitate the nanoparticles' absorption through the gastrointestinal tract. The results of differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR) revealed that drug and polymer stabilized each other by physical interactions between their functional groups. Both formulations presented an initial burst drug release of nearly 20% after 30min in phosphate buffer (pH = 7.4). After 24h, F-b did not release the drug completely, while F-a released the whole drug. Overall, nanoparticles with proper characteristics were obtained. This study puts forward the necessity of conducting further research in order to explore the intestinal absorption of these nanoparticles and the possibility of being utilized for oral administration of gentamicin sulfate.