Pharmacokinetics, Metabolism, and Partial Biodistribution of “Pincer Therapeutic” Nitazoxanide in Mice following Pulmonary Delivery of Inhalable Particles

Nitazoxanide (NTZ) induces autophagy in mammalian cells and also has mycobactericidal activity, displaying a two-pronged therapeutic effect, on the host as well as the pathogen. The pharmacokinetics and biodistribution of inhaled NTZ were investigated. Particles containing NTZ in a matrix of PLGA were prepared by spray drying. HPLC and LC-MS/MS methods were developed and validated. Particles were administered as inhalations to mice. Drug concentrations in plasma and tissues were estimated at different time points. Drug loading (∼36%), entrapment efficiency (>90%), and the conversion of NTZ into metabolites in plasma and lung homogenates were assessed satisfactorily by HPLC. NTZ pharmacokinetics and biodistribution following intravenous administration or inhalation were established by LC-MS. NTZ converted into tizoxanide (99% in 30 min) and other metabolites. Pulmonary delivery of NTZ entrapped in particles increased the half-life of the drug by factors of 3, 12, and 200 in the plasma, lung tissue, and alveolar macrophages, respectively. Targeted delivery and prolonged lung retention along with dose sparing of the kidneys was observed upon pulmonary delivery as compared to intravenous administration.