Preparation and In-vitro Evaluation of Rifampin-loaded Mesoporous Silica Nanoaggregates by an Experimental Design

The goal of this research is preparation, optimization and in-vitro evaluation of rifampin-loaded silica nanaoparticles in order to use in pulmonary drug delivery. Nanoparticles are exhaled because of thier small size, Preparation of nanoaggregates in micron-sized scale and re-disrpersion of them after the deposition in the lung is one approach in order to overcome this problem, which we used in this research. Rifampin was selected as a model lipophilic molecule since it is a well-documented and much used anti tuberculosis drug. A half factorial design was used to identify the significant parameters of spray drying process. The results showed that feed concentration, feed pH and interaction between feed flow rate and gas atomizer flow rate had statistically significant effect on the particle size of nanoaggregates. For optimization of spray drying process, the Box-Behnken design was employed and finally a quadratic equation which explains the relation between independent variables with aerodynamic diameter of nanoaggregates was obtained. Rifampin-loaded silica nanoaggregates underwent different in-vitro tests including: SEM, Aerosol performance and drug release. The in vitro drug release was investigated with buffer phosphate (pH=7.4). Regarding the drug release study a triphasic pattern of release was observed. The rifampin-loaded silica nanoaggregates was capable of releasing 90% drug content after 24h in combination patterns of release. The prepared rifampin-loaded nanoaggregates seem to have potential for use in a pulmonary drug delivery.