Inhaled dry powder formulations for treating tuberculosis.

Tuberculosis is the second leading cause of death from infectious diseases. Although antitubercular drugs have been traditionally administered orally, there is a growing interest in delivering drugs via the pulmonary route using nebulisers or dry powder inhalers. Drugs in dry powder inhalers (DPI) are stable and DPI are user-friendly compared to nebulisation which is time consuming, inconvenient and inefficient and requires special equipment. For tuberculosis treatment, drugs should target alveolar macrophages that harbour microorganisms and/or maintain high drug concentration at the infection site in the lung. Drug particles include micro-particles or nanoparticles. Powders can be engineered by micronisation, crystallisation, spray drying, freeze drying and particle coating approaches. The formulation may contain single or combination drugs. This paper will provide an update on current status of TB, its pathogenesis, current treatment strategies, shortcomings of current oral or parenteral delivery strategies, pulmonary delivery devices, advantages of pulmonary delivery of powder formulations, formulation approaches and pharmacokinetic studies of pulmonary delivery of powders for inhalation.