Design, Optimization and In vitro Assessment of Rifampicin Loaded Self-Nanoemulsifying Drug Delivery System

The aim of present investigation was to develop self-nanoemulsifying drug delivery system of rifampicin (RIF) using vegetable oils for improved drug release and tuberculostatic activity (TSA). A number of lipid-based formulations were developed using vegetable oils, polysorbate 80, and ethanol at different weight ratio. The formulations were optimized based on visual assessment, in vitro dissolution study, electro-physical characterization and transmission electron microscopic analysis. The optimized formulation was subjected to in vitro TSA study against two clinically RIF-sensitive strains of M. tuberculosis (Mtb) followed by accelerated stability evaluation. Visual observation ascertained the self-emulsification efficiency of all the emulsions (NEs) in terms of clarity, homogeneity, and phase separation. Dissolution study of RIF-loaded NEs revealed that complete (100%) drug release was obtained by RIF-NE7 within 45 min, whereas pure drug liberated maximum 59.6%. This enhanced drug release was attributed to self-nanoemulsification accomplished through its globule size (GS), poly dispersity index (PDI) and zeta potential (ZP) by 230.2 nm, 0.768 and -79.2 mV, respectively. The in vitro TSA study revealed that the dissolution samples of RIF-NE7 at 30 and 45 min were capable to inhibit the growth of Mtb strains, while pure RIF showed no inhibition till 120 min. Finally, the accelerated stability study indicated no significant variation of RIF-NE7 in aspect to its drug release pattern, GS and ZP. Observation of this study conferred that the newer lipid-based formulation would be a promising alternative to conventional rifampicin therapy to combat tuberculosis.