title: Influence of different polymers on crystallization tendency and dissolution behavior of cilnidipine in solid dispersions.
abstract: BACKGROUND
  Cilnidipine (CN) is a novel dihydropyridine calcium antagonist that is practically insoluble in aqueous media and exhibits a low oral bioavailability or limited clinical efficacy.
  
  
  OBJECTIVE
  This study investigated the effects of three commercial and chemically diverse polymers - PVP, PVP/VA and Soluplus - on crystallization tendency and in vitro dissolution profiles of CN in order to determine an optimum carrier for composing the preferred solid dispersion (SD) of CN.
  
  
  METHODS
  All these co-evaporated systems were characterized up to 3 months by thermoanalytical (DSC), crystallographic (POM, PXRD), microscopic (SEM) and spectroscopic (FTIR) techniques.
  
  
  RESULTS
  The results showed that the polymers could be sorted by their effects of inhibiting CN crystallization in the ascending order: Soluplus, PVP/VA, PVP. The sequence was in accordance with that of the strength of drug-polymer hydrogen bonds revealed by FTIR spectra. It could be ascribed to relative hydrogen-bonding acceptor strengths of N-vinylpyrrolidone moiety in the polymer molecules. On the other hand, all the SDs showed enhanced dissolution profiles compared to pure CN alone. On their effects of enhancing CN dissolution, the polymers could be sorted in the descending order: Soluplus, PVP, PVP/VA.
  
  
  CONCLUSIONS
  It implied that the dissolution behavior of CN could bear a close relationship to both hydration capacity and hydrogen-bonding interaction tendency of moieties of the polymers. It might suggest an optimal formulation for CN comprising both PVP and Soluplus.
authors.affiliation: Laboratory of Pharmaceutics, Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University , Nanjing , PR China and.
authors.forename: Chen
authors.initials: C
authors.lastname: Chen
authors.forename: Xiabing
authors.initials: X
authors.lastname: Xie
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.forename: Chen
authors.initials: C
authors.lastname: Zhou
authors.forename: Yang
authors.initials: Y
authors.lastname: Song
authors.forename: Zhixiang
authors.initials: Z
authors.lastname: Yan
authors.forename: Xinghao
authors.initials: X
authors.lastname: Yang
mesh_terms: D002121:Calcium Channel Blockers / Q000008:administration & dosage* / Q000737:chemistry; D002626:Chemistry, Pharmaceutical; D003460:Crystallization; D004095:Dihydropyridines / Q000008:administration & dosage* / Q000737:chemistry; D004337:Drug Carriers / Q000737:chemistry*; D004355:Drug Stability; D004356:Drug Storage; D006860:Hydrogen Bonding; D011092:Polyethylene Glycols / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D011145:Polyvinyls / Q000737:chemistry; D011205:Povidone / Q000737:chemistry; D011759:Pyrrolidines / Q000737:chemistry; D012995:Solubility; D013997:Time Factors; D014753:Vinyl Compounds / Q000737:chemistry
chemical_list: D002121:Calcium Channel Blockers; D004095:Dihydropyridines; D004337:Drug Carriers; D011108:Polymers; D011145:Polyvinyls; D011759:Pyrrolidines; D014753:Vinyl Compounds; C402301:poly(vinylpyrrolidone-co-vinyl-acetate); C572167:polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer; D011092:Polyethylene Glycols; C065927:cilnidipine; D011205:Povidone