The apparent plasticizing effect of polyethylene glycol (PEG) on the crystallinity of spray dried lactose/PEG composites

Research output: Contribution to journalArticle


Aqueous solutions of lactose and polyethylene glycol (PEG) were spray dried in a Buchi Model 191 spray dryer with the aim to investigate the effect of PEG on the crystallinity of the composite. A PEG concentration of 10.7% by weight of solids was studied for PEG 200, 600, 1500, 4000 and 8000. For PEG 200 and 4000 additional concentrations from 1.5-19.3% to 1.5-32.4%, respectively, were investigated. The spray dried composites were analysed with X-ray powder diffraction and modulating differential scanning calorimetry. The crystallinity of lactose in the composites varied from 0% to 60%, dependent on the molecular weight and concentration of PEG. Apparently, lactose crystallinity is promoted by low molecular weight and high concentration of the PEG. PEG did not affect the lactose glass transition temperature. It is suggested that lactose and PEG are solidified separately during spray drying and that partial crystallization of lactose is associated with effects of PEG on the rate of drying.


  • Kristina Mosén
  • Kjell Backstrom
  • Kyrre Thalberg
  • Torben Schaefer
  • Anders Axelsson
  • Hennina G. Kristensen
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Chemical Engineering


  • temperature, glass transition, lactose, spray drying, polyethylene glycol, crystallinity
Original languageEnglish
Pages (from-to)206-211
JournalEuropean Journal of Pharmaceutics and Biopharmaceutics
Issue number2
Publication statusPublished - 2006
Publication categoryResearch