title: Molecular motions in sucrose-PVP and sucrose-sorbitol dispersions-II. Implications of annealing on secondary relaxations.
abstract: OBJECTIVE
  To determine the effect of annealing on the two secondary relaxations in amorphous sucrose and in sucrose solid dispersions.
  
  
  METHODS
  Sucrose was co-lyophilized with either PVP or sorbitol, annealed for different time periods and analyzed by dielectric spectroscopy.
  
  
  RESULTS
  In an earlier investigation, we had documented the effect of PVP and sorbitol on the primary and the two secondary relaxations in amorphous sucrose solid dispersions (1). Here we investigated the effect of annealing on local motions, both in amorphous sucrose and in the dispersions. The average relaxation time of the local motion (irrespective of origin) in sucrose, decreased upon annealing. However, the heterogeneity in relaxation time distribution as well as the dielectric strength decreased only for β1- (the slower relaxation) but not for β2-relaxations. The effect of annealing on β2-relaxation times was neutralized by sorbitol while PVP negated the effect of annealing on both β1- and β2-relaxations.
  
  
  CONCLUSIONS
  An increase in local mobility of sucrose brought about by annealing could be negated with an additive.
authors.affiliation: Department of Pharmaceutics, University of Minnesota, Minneapolis, Minnesota, 55455, USA.
authors.forename: Sisir
authors.initials: S
authors.lastname: Bhattacharya
authors.forename: Sunny P
authors.initials: SP
authors.lastname: Bhardwaj
authors.forename: Raj
authors.initials: R
authors.lastname: Suryanarayanan
mesh_terms: D003460:Crystallization; D058266:Dielectric Spectroscopy; D004355:Drug Stability; D008956:Models, Chemical; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D044367:Phase Transition; D011205:Povidone / Q000737:chemistry*; D013012:Sorbitol / Q000737:chemistry*; D013395:Sucrose / Q000737:chemistry*; D013997:Time Factors
chemical_list: D004364:Pharmaceutical Preparations; D013012:Sorbitol; D013395:Sucrose; D011205:Povidone