title: [Drug release mechanism of famotidine time-controlled release pellets].
abstract: OBJECTIVE
  To study the drug release mechanism of famotidine time-controlled release pellets and to explore the mechanism of "organic acid-induced type drug delivery system".
  
  
  METHODS
  The effects of dissociated and undissociated forms of succinic acid on the drug release behavior of famotidine time-controlled release pellets were studied from the following aspects: ion-exchange reaction, hydration, etc.
  
  
  RESULTS
  The dissociated succinic acid created new ionic circumstances by ion-exchange reaction with Eudragit RS100. Whereas undissociated succinic acid increased the flexibility of the film by distribution in the hydrophobic segment of Eudragit RS100. Effects of both forms of the succinic acid could improve the hydration of Eudragit RS film. As a result, the permeability of the film was improved evidently.
  
  
  CONCLUSIONS
  The lag time of famotidine time-controlled release pellets is induced by the hydrophobicity of the film. After water dissolve the organic acid, the dissociated and undissociated forms of succinic acid interact with the film through different ways. These interactions can change the structure of the film. Therefore the permeability of the film will be improved markedly.
authors.affiliation: New Drug Research and Development Co. Ltd., North China Pharmaceutical Group Corp., Shijiazhuang 050015, China. zl51@163.com
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Da-wei
authors.initials: DW
authors.lastname: Chen
authors.forename: Zi-bin
authors.initials: ZB
authors.lastname: Gao
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D000897:Anti-Ulcer Agents / Q000737:chemistry / Q000493:pharmacokinetics; D003692:Delayed-Action Preparations / Q000737:chemistry / Q000493:pharmacokinetics*; D015738:Famotidine / Q000737:chemistry / Q000493:pharmacokinetics*; D007474:Ion Exchange; D019802:Succinic Acid / Q000737:chemistry*; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D000180:Acrylic Resins; D000897:Anti-Ulcer Agents; D003692:Delayed-Action Preparations; D014867:Water; C050528:Eudragit RS; D015738:Famotidine; D019802:Succinic Acid