title: Inhalable microparticles as carriers for pulmonary delivery of thymopentin-loaded solid lipid nanoparticles.
abstract: OBJECTIVE
  Microparticles containing solid lipid nanoparticles (SLNs) are receiving increased attention as carriers for the lung delivery of the SLNs. Thus, we aim to prepare the hybrid microparticles and thoroughly evaluate their feasibility for the pulmonary drug delivery.
  
  
  METHODS
  The microparticles were prepared by co-spray-drying the thymopentin (TP5)-loaded SLNs with bulking agents. Thereafter, we systematically estimated the potential of the microparticles as the carriers for the pulmonary delivery of the SLNs, including the investigations of their characteristics, aerodynamic properties, pharmacokinetics and pharmacodynamics.
  
  
  RESULTS
  The spherical and hollow microparticles presented a size of 4.1 +/- 0.1 microm and a low tap density of 0.175 +/- 0.02 g/cm(3). In addition, the microparticles showed a high aerosolization efficiency (emitted dose of 98.0% +/- 1.23% and respirable fraction of 51.07% +/- 1.21%). Furthermore, the SLNs could be easily recovered from the microparticles without essential changes on their characteristics and the drug release behavior. The pharmacokinetic and pharmacodynamic studies suggested that, compared to i.v. TP5 solution, the bioavailability and therapeutic efficacy of TP5 were remarkably strengthened after the pulmonary administration of the microparticles.
  
  
  CONCLUSIONS
  Taken together, we believe the microparticles were suitable for inhalation and possessed an ample potential for the pulmonary delivery of the SLNs.
authors.affiliation: Key Laboratory of Drug Targeting and Novel Drug Delivery Systems West China School of Pharmacy, Sichuan University, No. 17, Block 3, Southern Renmin Road, Chengdu 610041, People's Republic of China.
authors.forename: Yan-Zhen
authors.initials: YZ
authors.lastname: Li
authors.forename: Xun
authors.initials: X
authors.lastname: Sun
authors.forename: Tao
authors.initials: T
authors.lastname: Gong
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
authors.forename: Jiao
authors.initials: J
authors.lastname: Zuo
authors.forename: Zhi-Rong
authors.initials: ZR
authors.lastname: Zhang
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics* / Q000627:therapeutic use; D000280:Administration, Inhalation; D000818:Animals; D016516:CD4-CD8 Ratio; D004337:Drug Carriers / Q000737:chemistry*; D004355:Drug Stability; D007153:Immunologic Deficiency Syndromes / Q000097:blood / Q000188:drug therapy / Q000276:immunology; D008055:Lipids / Q000737:chemistry*; D008168:Lung / Q000378:metabolism*; D016131:Lymphocyte Subsets / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D018613:Microscopy, Confocal; D053758:Nanoparticles / Q000737:chemistry*; D051381:Rats; D017208:Rats, Wistar; D013482:Superoxide Dismutase / Q000378:metabolism; D013499:Surface Properties; D016305:Thymopentin / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics* / Q000627:therapeutic use
chemical_list: D000276:Adjuvants, Immunologic; D004337:Drug Carriers; D008055:Lipids; D013482:Superoxide Dismutase; D016305:Thymopentin