Development of respirable rifampicin loaded bovine serum albumin formulation for the treatment of pulmonary tuberculosis

Abstract

Rifampicin (RIF) is the first-line drug used for the treatment of tuberculosis. The limitations of this high dose drug can be strategically tackled by dose reduction. Rifampicin loaded bovine serum albumin nanoparticles (RIF-BSA NPs) were prepared by desolvation method using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) as the cross-linking agent. Use of EDC reduced the time for cross-linking and simplified the preparation method. The prepared formulation showed particle size of 232 ± 5.4 nm, zeta potential of −30.1 ± 0.2 mV, entrapment efficiency (EE) 86.2 ± 3.9% with 30.4 ± 2.7% drug loading (DL). A biphasic in vitro release pattern was observed for RIF-BSA NPs with initial burst release followed by sustained release for 72 h. A dry powder inhaler (DPI) formulation was then obtained using spray drying. The mass median aerodynamic diameter (MMAD) and fine particle fraction (FPF) were found to be 3.21 ± 1.2 μm and 52.49 ± 3.6%, respectively after characterization using Anderson cascade impactor. The attained results confirm suitability of the designed formulation for pulmonary delivery of RIF. RIF-BSA NPs demonstrated enhanced in vitro therapeutic efficacy assessed by MTb killing assay compared to the free drug suggesting the possibility for dose reduction. Further, FITC-labelled RIF BSA NPs could be efficiently taken up by RAW264.7 cells infected with Mycobacterium tuberculosis (H37rv), as confirmed using fluorescence microscopy. The results obtained from these studies suggest that the use of RIF-BSA NPs DPI formulation can be a promising strategy for the treatment of pulmonary tuberculosis.