CONICET | Buscador de Institutos y Recursos Humanos

The objective of this work was the development of liposomes for the delivery of poorly water-soluble drugs, Sulfamerazine (SMR) and Indomethacin (INM). Liposomes are colloidal vesicles of nanometric size composed of lipid bilayers surrounding aqueous compartments. Hydrophobic drugs can be incorporated in their lipid bilayer. 1, 2, 3, 4 Drug load and unload phosphatidylcholine (PC): cholesterol (CHO) liposomes were prepared by the thin film hydration method: dispersion of lipids and drugs, evaporation, exposition to a stream of nitrogen and hydration with a Phosphate Buffer solution (PBS). The particle size, polidispersity and zeta potential were determined at 25 oC. The interaction of the drugs with the liposomes components was determined by NMR-H1 spectroscopy. The integrity was evaluated by measuring the retention (%) of calcein in the vesicles at 37 oC for 48 h by fluorescence intensity measurement. The molar ratio of drug encapsulated over the total lipid concentration (D/L) was determined by UV-spectroscopy and a phospholipid colorimetric assay (Stewart, 1980) was applied. The particle size of all liposomes were in the range of 31.1-115 nm, the values of polidispersity were around 0.2 indicating that monodispersed systems were obtained and the zeta potential values of unload, SMR load and INM load liposomes were (-0.34 to -0.03 mV), (-2.9 to -0.07 mV) and (-0.41 to -0.09 mV), respectively. The NMR studies suggested the incorporation of the drug inside the lipid bilayer. The retention of unload, SMR load and INM load vesicles were 80, 80 and 95%, respectively, indicating the high stability of the liposomes. The higher entrapment values of SMR and INM were 308.98 and 10.14 mmol/mol, respectively. In conclusion, it was possible to obtain liposomes for the delivery of SMR and INM that presented small size, high stability and high drug entrapment, suggesting to be a promising strategy for improving the bioavailability of these drugs.