Pulmonary drug delivery systems for tuberculosis treatment

Tuberculosis (TB) remains a major global health problem as it is the second leading cause of death from an infectious disease worldwide, after the human immunodeficiency virus (HIV). Conventional treatments fail either because of poor patient compliance to the drug regimen or due to the emergence of multidrug-resistant tuberculosis. The aim of this review is to give an update on the information available on tuberculosis, its pathogenesis and current antitubercular chemotherapies. Direct lung delivery of anti-TB drugs using pulmonary delivery systems is then reviewed since it appears as an interesting strategy to improve first and second line drugs. A particular focus is place on research performed on inhalable dry powder formulations of antitubercular drugs to target alveolar macrophages where the bacteria develop. Numerous studies show that anti-TB drugs can be incorporated into liposomes, microparticles or nanoparticles which can be delivered as dry powders to the deep lungs for instantaneous, targeted and/or controlled release. Treatments of infected animals show a significant reduction of the number of viable bacteria as well as a decrease in tissue damage. These new formulations appear as interesting alternatives to deliver directly drugs to the lungs and favor efficient TB treatment.