title: [Swelling property of common hydrophilic polymers and their use in push-pull osmotic-pump tablets].
abstract: OBJECTIVE
  To investigate the feasibility of swelling hydrogel instead of polyethylene oxide as swelling polymer in push-layer of push-pull osmotically controlled-release tablets.
  
  
  METHODS
  The swelling patterns of tablets made of pure polymers were studied by immerging the tablets into purified water and testing their size at different time points. The push-pull osmotic-pump tablets were prepared and their release patterns in vitro were studied and compared by their similar factor (f2).
  
  
  RESULTS
  Tablets with different swelling materials all showed satisfying release pattern in vitro and their release ratio at 12 h were all above 80%.
  
  
  CONCLUSIONS
  With its release rate and cumulative release percentage at 12 h, the mixture of HPMC K15M and CMCNa in ratio of 1:1 is the best choice instead of polyethylene oxide as swelling polymer in push-layer.
authors.affiliation: College of Pharmaceutics, Ningxia Medical University, Yinchuan 750004, China. wangwenpingg@sina.com
authors.forename: Wenping
authors.initials: W
authors.lastname: Wang
authors.forename: Xiuqiong
authors.initials: X
authors.lastname: Xie
authors.forename: Dajian
authors.initials: D
authors.lastname: Yang
authors.forename: Xinzi
authors.initials: X
authors.lastname: Chen
mesh_terms: D002626:Chemistry, Pharmaceutical; D004337:Drug Carriers / Q000737:chemistry*; D009995:Osmosis; D011108:Polymers / Q000737:chemistry*; D013607:Tablets; D014867:Water / Q000737:chemistry*
chemical_list: D004337:Drug Carriers; D011108:Polymers; D013607:Tablets; D014867:Water