The Safety of Tuberculosis Treatments by Oral Inhalation

The inhaled route of delivery has always been associated with the considerable challenge of getting the drug to its target. The lungs are a highly complex organ designed to filter inspired air, with many different cell types contributing to their function. Furthermore, the lungs may change dramatically when afflicted by disease resulting in an internal environment that works against the drug reaching and interacting successfully with the target. For targets in the upper airways this will have lesser significance, but drug delivery to the deep lung may be impeded by changes such as mucus hyper-secretion or thickening or airway narrowing. In order to interpret toxicology findings it is necessary to reconcile test sensitivity, background biological variation, normal responses to inhaled materials and drug or medicine-specific adverse effects. Identification of adverse end-points is an area where better control data sets might help discern true adverse effects from a normal physiological lung response. The lung responds acutely to inhalation of irritant materials by hyper-secretion of mucus, chemokine release, inflammatory cell recruitment and cough and collectively these may be characterized as non-specific irritancy.