title: Investigation of solute permeation across hydrogels composed of poly(methyl vinyl ether-co-maleic acid) and poly(ethylene glycol).
abstract: OBJECTIVE
  Swelling kinetics and solute permeation (theophylline, vitamin B(12) and fluorescein sodium) of hydrogels composed of poly(methyl vinyl ether-co-maleic acid) (PMVE/MA) and poly(ethylene glycol) (PEG) are presented.
  
  
  METHODS
  The effects of PMVE/MA and PEG 10 000 content on swelling behaviour (percentage swelling, the type of diffusion and swelling rate constant) were investigated in 0.1 m phosphate buffer. Network parameters, such as average molecular weight between crosslinks (M(c)) and crosslink density, were evaluated.
  
  
  RESULTS
  The percentage swelling and M(c) of hydrogels increased with decrease in PMVE/MA content, where the water diffusion mechanism into the hydrogels was Class-II type. In contrast, increase in PMVE/MA content caused an increase in the crosslink density. Permeation of theophylline, vitamin B(12) and fluorescein sodium, with increasing hydrodynamic radii, was studied through the equilibrium swollen hydrogels composed of PMVE/MA and PEG. In general, the permeability and diffusion coefficients of all three solutes decreased with increase in the PMVE/MA content. In addition, permeability and diffusion coefficient values increased with decreases in the hydrodynamic radii of the solute molecules.
  
  
  CONCLUSIONS
  The hydrogels have shown a change in swelling behaviour, crosslink density, M(c) and solute permeation with change in PMVE/MA content, thus suggesting a potential application in controlled drug-delivery systems.
authors.affiliation: School of Pharmacy, Queens University Belfast, Northern Ireland, UK.
authors.forename: Thakur Raghu
authors.initials: TR
authors.lastname: Raj Singh
authors.forename: A David
authors.initials: AD
authors.lastname: Woolfson
authors.forename: Ryan F
authors.initials: RF
authors.lastname: Donnelly
mesh_terms: D002626:Chemistry, Pharmaceutical; D004058:Diffusion; D016503:Drug Delivery Systems / Q000379:methods*; D019793:Fluorescein; D020100:Hydrogels / Q000737:chemistry*; D008738:Methyl Ethers / Q000737:chemistry*; D008970:Molecular Weight; D010316:Particle Size; D010539:Permeability; D011092:Polyethylene Glycols / Q000737:chemistry*; D011145:Polyvinyls / Q000737:chemistry*; D012996:Solutions; D013806:Theophylline; D014805:Vitamin B 12; D014867:Water / Q000737:chemistry
chemical_list: D020100:Hydrogels; D008738:Methyl Ethers; D011145:Polyvinyls; D012996:Solutions; C510739:poly(vinyl methyl ether); D014867:Water; D011092:Polyethylene Glycols; D013806:Theophylline; D014805:Vitamin B 12; D019793:Fluorescein