Preparation of solid lipid nanoparticles of furosemide-silver complex and evaluation of antibacterial activity

Overuse and misuse of antibiotics in clinics and poor new antibiotic pipeline in pharmaceutical industries have contributed to antibiotic crisis. Silver complexes are effective as broad-spectrum antibiotics due to chemical nature. Furosemide-silver complex (Ag-FSE) has been recently reported to have antibacterial activity that is, however, limited by its poor solubility in water and majority of organic solvents. Solid lipid nanoparticles (SLNs) offer advantages such as controlled and sustained release, enhanced solubility, scale-up and, biocompatibility. Present study aims to encapsulate Ag-FSE into SLNs and evaluate its sustained and improved antibacterial activity. Ag-FSE SLNs were prepared using hot homogenization and ultrasonication method. Size, polydispersity index and zeta potential of Ag-FSE SLNs, evaluated using dynamic light scattering, were 129.8 +/- 38.5 nm, 0.114 +/- 0.033 and -23.9 +/- 3.62 mV, respectively. Ag-FSE SLNs exhibited high encapsulation efficiency (similar to 93%) and drug loading (similar to 9.3%). Shape of Ag-FSE SLNs was roughly spherical with smooth surface. In vitro release studies confirmed that encapsulation of Ag-FSE into SLNs resulted in sustained release of Ag-FSE over 96 h. Results confirmed 2-fold and 4-fold enhancement of activity against Pseudomonas aeruginosa and Staphylococcus aureus, respectively. In conclusion, Ag-FSE SLNs can be considered as promising topical antibacterial agent against bacterial infections.