Kett, Victoria; (2000) An Investigation into Amorphous Sucrose Systems Using Modulated Temperature Differential Scanning Calorimetry. Doctoral thesis (Ph.D), UCL (University College London).

Text An_investigation_into_amorphou.pdf Download (22MB)

Abstract

This study investigated the glass transitional region of sucrose solutions and of freeze dried sucrose systems. Freeze drying is often used in the pharmaceutical industry as a method of preparing dosage forms that would otherwise be unstable. The freezing stage of the process may be deleterious to such compounds unless a glass-forming cryoprotectant, such as sucrose, is added. Glass-formers exhibit a glass transition, (Tg), that can be measured using thermal techniques. The glass transitional region of frozen sucrose systems is complex, displaying two transitions. Modulated temperature differential scanning calorimetry (MTDSC) was used to probe the region. It was found that the lower of the two transitions is the true Tg, while the upper is caused by the dissolution of ice. The effect of annealing, the process during which a glassy material is stored below its Tg and allowed to relax, was investigated. Increasing the annealing time led to an increase in the endothermic relaxation accompanying the Tg. However, this reached a maximum after a short annealing period. Dielectric spectroscopy was also used to study this process. Again, increasing annealing time led to an increase in sample response that then tailed off. The role of the product Tg in the stability of the freeze dried product was investigated. A protein formulation was freeze dried for varying lengths of time. The link between the water content, the Tg of the product and the stability of the protein was explored. The effect of a change in buffer on the protein stability was also investigated. The effect of storage was also studied. Material was stored under different conditions of relative humidity and temperature. Tg proved to be a poor guide to the stability of the protein. However it could be used to determine the mobility in the formulation.

Download activity - last month

Export as CSVXMLJSON

Download activity - last 12 months

Export as JSONCSVXML

Downloads by country - last 12 months

Export as XMLCSVJSON

Archive Staff Only

View Item