title: HyperDSC studies of amorphous polyvinylpyrrolidone in a model wet granulation system.
abstract: Measurements of the properties of amorphous materials are very important to help in the understanding of how materials behave during manufacture, storage and use of medicines. However, there are few methods that are suited to the study of amorphous materials, especially if in multi-component systems or model formulations. The goal here was to explore the potential for the use of HyperDSC to study a model granulation system. It was found that the sensitivity of HyperDSC was such that the glass transition (Tg) of polyvinylpyrrolidone (PVP) could be detected in granules made with realistic levels of this binder. The measured Tg in the granules, even after drying, was very different to that of PVP alone and to PVP in physical mixtures with lactose. It is argued that the granulation process has resulted in the dissolution of some lactose and that the amorphous binder holding the granules together is in fact a solid dispersion of PVP and lactose. Based on the standard Gordon-Taylor equation it was estimated that the solid dispersion contained 50% of PVP and lactose. Given that solid dispersions have a tendency to crystallise on storage, it could be expected that changes in the binder properties will occur with time after granulation. We believe that this is the first measurement of in situ properties of a binder in this way and opens the possibility of studies on formulated systems.
authors.affiliation: Department of Pharmaceutics, School of Pharmacy, University of London, 29-39 Brunswick Square, London WC1N 1AX, United Kingdom. Graham.Buckton@ulsop.ac.uk
authors.forename: Graham
authors.initials: G
authors.lastname: Buckton
authors.forename: Akintayo A
authors.initials: AA
authors.lastname: Adeniyi
authors.forename: Mark
authors.initials: M
authors.lastname: Saunders
authors.forename: Ameet
authors.initials: A
authors.lastname: Ambarkhane
mesh_terms: D002152:Calorimetry, Differential Scanning; D002626:Chemistry, Pharmaceutical; D005079:Excipients / Q000737:chemistry; D007785:Lactose / Q000737:chemistry; D011205:Povidone / Q000737:chemistry*; D012995:Solubility
chemical_list: D005079:Excipients; D011205:Povidone; D007785:Lactose