title: Inhalable particles containing rapamycin for induction of autophagy in macrophages infected with Mycobacterium tuberculosis.
abstract: We investigated whether particles suitable for delivery to alveolar macrophages may provide a means of targeting rapamycin, an inducer of autophagy, to alveolar macrophages as a host-directed antituberculosis agent. Inhalable particles were prepared by spray-drying and characterized using laser scattering and electron microscopy. Their aerodynamic diameter was calculated from bulk and tapped densities. In vitro drug release was studied in PBS containing 1% SDS. In vitro uptake of particles by THP-1 derived macrophages was studied by flow cytometry. Cytotoxicity of the particles toward macrophages and their efficacy against intracellular Mycobacterium tuberculosis were studied using a methyltetrazolium assay and counting bacterial colonies obtained when cell lysates were plated on agar. The encapsulation efficiency was 88.8 ± 1.13% and drug content 22 ± 4% w/w. The particles had a median diameter of 2.88 ± 0.8 μm and appeared as collapsed spheres. Their calculated aerodynamic diameter was about 1 μm. In vitro drug release from the particles was first-order and extended beyond 10 days. Flow cytometry indicated that the particles were taken up by macrophages within 3 h. Macrophages exposed to the particles or rapamycin in solution at a concentration of 100 μg/mL over a 24 h period maintained 79.37 ± 0.72% and 58.33 ± 1.39% viability, respectively. Efficacy studies concluded that particles were more effective in clearing intracellular mycobacteria than rapamycin in solution. It was concluded that the preparation was suitable for formulating as a dry powder inhalation to test efficacy of inhaled, macrophage-targeted rapamycin against TB.
authors.affiliation: Pharmaceutics Division, CSIR-Central Drug Research Institute , Sector 10A, Janakipuram Extension, Mohiuddinpur, Lucknow 226031, India.
authors.forename: Anuradha
authors.initials: A
authors.lastname: Gupta
authors.forename: Garima
authors.initials: G
authors.lastname: Pant
authors.forename: Kalyan
authors.initials: K
authors.lastname: Mitra
authors.forename: Jitender
authors.initials: J
authors.lastname: Madan
authors.forename: Manish K
authors.initials: MK
authors.lastname: Chourasia
authors.forename: Amit
authors.initials: A
authors.lastname: Misra
mesh_terms: D000280:Administration, Inhalation; D001343:Autophagy / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D016503:Drug Delivery Systems; D006801:Humans; D019344:Lactic Acid / Q000008:administration & dosage*; D008264:Macrophages / Q000378:metabolism* / Q000382:microbiology; D008863:Microspheres; D009169:Mycobacterium tuberculosis / Q000187:drug effects*; D010316:Particle Size; D011100:Polyglycolic Acid / Q000008:administration & dosage*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D020123:Sirolimus / Q000008:administration & dosage* / Q000737:chemistry / Q000493:pharmacokinetics; D012995:Solubility
chemical_list: D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D020123:Sirolimus