title: Assessment of the drug loading, in vitro and in vivo release behavior of novel pH-sensitive hydrogel.
abstract: BACKGROUND
  As a glucocorticoid drug, dexamethasone has good therapeutic effects for ulcerative colitis. pH-sensitive hydrogels could make conventional changes of volume in response with different pH values. Meanwhile, they could load drugs depending on its internal three-dimensional network structure.
  
  
  OBJECTIVE
  Appropriate methods were used to improve the drug-loading capacity of hydrogel and exploring the colon-targeting character of dexamethasone hydrogel.
  
  
  METHODS
  Different solvents (ethanol and 1,2-propanediol) were employed to dissolve dexamethasone as well as hydrogel monomer materials (poly(ethylene glycol) methyl ether (MPEG)-poly(lactide acid)-acryloyl chloride macromonomer, itaconic acid (IA) and MPEG-methacrylate), then mixing them together to prepare hydrogel through the heat-initiated free radical polymerization method. Differential scanning calorimetry and X-ray diffraction methods were used to verify whether dexamethasone was loaded into hydrogels. In vitro drug release behavior and in vivo pharmacokinetic study were also investigated in detail.
  
  
  RESULTS
  Dexamethasone was successfully loaded into hydrogel, and its loading capacity was improved (5 mg/g). Both the in vitro release study and the in vivo pharmacokinetic study showed the good colon-targeting character of the pH-sensitive P(LE-IA-MEG) hydrogel (T max = 1.0 h, C max = 2.16 µg/ml of dexamethasone; T max = 3.9 h, C max = 0.43 µg/ml of dexamethasone hydrogel).
  
  
  CONCLUSIONS
  Dexamethasone could be targeted to the colon site by P(LE-IA-MEG) hydrogel, thereby improving its therapeutic effect and reduce its side effects.
  
  
  CONCLUSIONS
  P(LE-IA-MEG) hydrogel might have great potential application in colon-targeted drug delivery systems.
authors.affiliation: a School of Pharmacy, Health Science Center , Xi'an Jiaotong University , Xi'an , Shaanxi , China and.
authors.forename: Kai
authors.initials: K
authors.lastname: Dong
authors.affiliation: b Depertment of Pharmacy, The first Affiliated Hospital of Medical College , Xi'an Jiaotong University , Xi'an , Shaanxi , China.
authors.forename: Yalin
authors.initials: Y
authors.lastname: Dong
authors.affiliation: a School of Pharmacy, Health Science Center , Xi'an Jiaotong University , Xi'an , Shaanxi , China and.
authors.forename: Cuiyu
authors.initials: C
authors.lastname: You
authors.affiliation: a School of Pharmacy, Health Science Center , Xi'an Jiaotong University , Xi'an , Shaanxi , China and.
authors.forename: Wei
authors.initials: W
authors.lastname: Xu
authors.affiliation: a School of Pharmacy, Health Science Center , Xi'an Jiaotong University , Xi'an , Shaanxi , China and.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Huang
authors.affiliation: a School of Pharmacy, Health Science Center , Xi'an Jiaotong University , Xi'an , Shaanxi , China and.
authors.forename: Yan
authors.initials: Y
authors.lastname: Yan
authors.affiliation: a School of Pharmacy, Health Science Center , Xi'an Jiaotong University , Xi'an , Shaanxi , China and.
authors.forename: Lu
authors.initials: L
authors.lastname: Zhang
authors.affiliation: a School of Pharmacy, Health Science Center , Xi'an Jiaotong University , Xi'an , Shaanxi , China and.
authors.forename: Ke
authors.initials: K
authors.lastname: Wang
authors.affiliation: a School of Pharmacy, Health Science Center , Xi'an Jiaotong University , Xi'an , Shaanxi , China and.
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Xing
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D003106:Colon / Q000187:drug effects; D003907:Dexamethasone / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D016503:Drug Delivery Systems; D020100:Hydrogels; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid; D011092:Polyethylene Glycols; D011100:Polyglycolic Acid; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers; D051381:Rats; D012995:Solubility; D012997:Solvents
chemical_list: D000893:Anti-Inflammatory Agents; D020100:Hydrogels; D011108:Polymers; D012997:Solvents; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D011092:Polyethylene Glycols; D003907:Dexamethasone
keywords: Dexamethasone; drug-loading; in vitro drug release study; in vivo pharmacokinetic study; pH-sensitive