Preparation and characterization of rifampin loaded mesoporous silica nanoparticles as a potential system for pulmonary drug delivery

The goal of this research is to determine the feasibility of loading rifampin into mesoporous silica nanoparticles. Rifampin was selected as a model lipophilic molecule since it is a well-documented and much used anti tuberculosis drug. The mesoporous silica nanoparticles were prepared by using tetraethyl ortho silicate and cetyltrimethyl ammonium bromide (as surfactant). The prepared nanoparticles were characterized in terms of their particle size measurement and porosimetry. The results showed that the particle size is 218 ± 46 nm (mean ± SD) and surface area is 816 m(2)g(-1). In order to load rifampin within the mesopores, adsorption experiments using three different solvents (methanol, water and dimethyl sulfoxide) were carried out. The loading procedure resulted in a significant improvement in the amount of rifampin loaded into mesoporous silica nanoparticles and methanol was found to be a suitable solvent, providing a drug entrapment efficiency of 52 %. Rifampin loaded nanoparticles underwent different in-vitro tests including, SEM and drug release. The in-vitro drug release was investigated using buffer phosphate (pH=7.4). Regarding the drug release study, a biphasic pattern of release was observed. The drug-loaded mesoporous silica nanoparticles were capable of releasing 95% of their drug content after 24 h, following a faster release in the first four hours. The prepared rifampin loaded nanoparticles seem to have potential for use as a pulmonary drug delivery.