title: Complexation of a poly-L-arginine with low molecular weight heparin enhances pulmonary absorption of the drug.
abstract: OBJECTIVE
  This study tests the hypothesis that complexation between a cationic polymer, poly-L-arginine (PLA), and an anionic drug, low molecular weight heparin (LMWH), enhances pulmonary absorption and reduces the epithelial toxicity.
  
  
  METHODS
  Enoxaparin, a LMWH, was complexed with PLAs of different molecular weights at varying concentrations. The resulting complexes were characterized by measuring particle size and zeta potential, and by quantitating the interactions between PLA and enoxaparin using an azure A assay. Changes in transepithelial electrical resistance (TEER) and cytotoxicity induced by enoxaparin-PLA complex were investigated in Calu-3 cells. Pulmonary absorption of LMWH was determined by measuring plasma anti-factor Xa levels. A bronchoalveolar lavage (BAL) study was performed to investigate if the PLA-based formulations caused any cellular or biochemical changes in the lungs.
  
  
  RESULTS
  The particle size of enoxaparin-PLA complexes decreased and the zeta potential values of the complex became less negative as the concentration of positively charged PLA in the complex increased. In vitro experiments suggest that addition of enoxaparin-PLA complex to the apical side of a polarized cell monolayer results in a significant increase in permeability to 14C-mannitol and a decrease in TEER. Pulmonary formulations of enoxaparin plus 0.0125% or 0.0625% PLA of molecular weight 93 kDa led to a twofold increase in the relative bioavailability of LMWH compared to the control (enoxaparin plus normal saline). The BAL study showed that the enoxaparin-PLA complex formulation did not elicit any significant increases in marker enzyme activities compared to the normal saline-treated or untreated control groups.
  
  
  CONCLUSIONS
  PLA could be used as a carrier for the pulmonary delivery of LMWH.
authors.affiliation: Department of Pharmaceutical Sciences, School of Pharmacy, Health Sciences Center, Texas Tech University, 1300 Coulter Drive, Amarillo, Texas, 79106, USA.
authors.forename: Amit
authors.initials: A
authors.lastname: Rawat
authors.forename: Tianzhi
authors.initials: T
authors.lastname: Yang
authors.forename: Alamdar
authors.initials: A
authors.lastname: Hussain
authors.forename: Fakhrul
authors.initials: F
authors.lastname: Ahsan
mesh_terms: D000818:Animals; D000925:Anticoagulants / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics* / Q000633:toxicity; D001682:Biological Availability; D002460:Cell Line; D002463:Cell Membrane Permeability; D016764:Cell Polarity; D002470:Cell Survival; D002626:Chemistry, Pharmaceutical; D004337:Drug Carriers; D004339:Drug Compounding; D017097:Electric Impedance; D017984:Enoxaparin / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics* / Q000633:toxicity; D004847:Epithelial Cells / Q000378:metabolism; D065427:Factor Xa Inhibitors; D008168:Lung / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008353:Mannitol / Q000378:metabolism; D008970:Molecular Weight; D010316:Particle Size; D010455:Peptides / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000925:Anticoagulants; D004337:Drug Carriers; D017984:Enoxaparin; D065427:Factor Xa Inhibitors; D010455:Peptides; C015462:polyarginine; D008353:Mannitol