Isoxyl particles for pulmonary delivery: In vitro cytotoxicity and potency

Pulmonary delivery of isoxyl may increase drug efficacy by targeting alveolar macrophages which are host cells for Mycobacteria. Isoxyl microparticles (1–2 μm) were obtained by antisolvent precipitation and simultaneous spray drying method. The controls were made by mixing isoxyl solution in DMSO with cell culture media. Depending on the drug concentration, either isoxyl solution or nanosuspension was obtained in these controls. In the study, MTT (methylthiazol tetrazolium) and LDH (lactose dehydrogenase) assays were utilized to test cytotoxicity of these particle suspensions or solutions toward macrophages. Isoxyl microparticles and controls in concentrations up to 100 μg/ml were not toxic to macrophages. Both isoxyl microparticle suspensions and controls showed bactericidal activity, as estimated by death of mycobacteria inside the macrophages, at a concentration of 5 μg/ml.