Pulmonary delivery of rifampicin-loaded soluplus micelles against Mycobacterium tuberculosis

Abstract

Abstract Tuberculosis (TB) stands as the second “most deadly infectious disease” behind AIDS. Rifampicin (RIF) represents one of the most effective anti-TB drugs of the “short-term” oral TB therapy. However, the main limitations of the oral treatment are related with the lack of patient adherence and the development of multi-drug resistant Mycobacterium tuberculosis (Mtb) strains. Recently, the pulmonary administration of anti-TB drugs has become an attractive alternative to improve TB therapy. Hence, we have developed a respirable nanocarrier based on RIF-loaded polymeric micelles (PMs), employing a commercially available graft-copolymer of poly (vinyl caprolactam)-poly (vinyl acetate)-poly (ethylene glycol) (Soluplus). The RIF apparent aqueous solubility was increased (14.3-fold) and the micellar system was ranged in the nanoscale (~107\u202fnm). Then, according to its in vitro aerodynamic behavior, our nanoformulation represented a suitable system for deep lung drug delivery. Interestingly, these inhalable RIF-loaded PMs enhanced (up to 2.5-fold) the in vitro drug microbicidal activity in Mtb-infected THP-1 macrophages versus a RIF solution. In addition, the biodistribution studies of the radiolabelled (99mTc) PMs demonstrated their lung accumulation over 24\u202fhs in rats. Overall, this novel nanoformulation stands as an attractive platform for a potential inhalable TB therapy.