title: The apparent plasticizing effect of polyethylene glycol (PEG) on the crystallinity of spray dried lactose/PEG composites.
abstract: Aqueous solutions of lactose and polyethylene glycol (PEG) were spray dried in a Büchi 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.
authors.affiliation: Department of Pharmaceutics, The Danish University of Pharmaceutical Sciences, Copenhagen Ø, Denmark.
authors.forename: Kristina
authors.initials: K
authors.lastname: Mosén
authors.forename: Kjell
authors.initials: K
authors.lastname: Bäckström
authors.forename: Kyrre
authors.initials: K
authors.lastname: Thalberg
authors.forename: Torben
authors.initials: T
authors.lastname: Schaefer
authors.forename: Anders
authors.initials: A
authors.lastname: Axelsson
authors.forename: Henning G
authors.initials: HG
authors.lastname: Kristensen
mesh_terms: D002152:Calorimetry, Differential Scanning / Q000379:methods; D003188:Composite Resins / Q000737:chemistry; D003460:Crystallization / Q000379:methods; D003890:Desiccation / Q000379:methods; D006813:Humidity; D007785:Lactose / Q000031:analogs & derivatives / Q000737:chemistry*; D008970:Molecular Weight; D010968:Plasticizers / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D013678:Technology, Pharmaceutical / Q000379:methods*; D044366:Transition Temperature; D014961:X-Ray Diffraction / Q000379:methods
chemical_list: D003188:Composite Resins; D010968:Plasticizers; D011092:Polyethylene Glycols; D007785:Lactose