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Critical Temperatures in Freeze-Drying of Carbohydrates with Protein and Glycine
2000 (English)Independent thesis Basic level (degree of Bachelor)Student thesis
Abstract [en]

Institutionen för Kemi 2000-03-22 Critical Temperatures in Freeze-Drying of Carbohydrates with Protein and Glycine Diploma Thesis, 20p Performed at Pharmacia & Upjohn, Stockholm Author: Fredrik Carlén Examinator:Thomas Nilsson, Assoc. Professor Karlstad University Supervisor: Jonas Fransson, Ph.D. in Pharm. Pharmacia & Upjohn -- The purpose of this study was to determine the collapse temperatures for a number of different protein- and glycine/carbohydrate-mixtures to be used for freeze drying optimizations. Furthermore the aim was to investigate how the collapse temperature is affected by the weight ratio protein:carbohydrate and glycine:carbohydrate respectivly. Human growth hormone (hGH) was used as a model protein. hGH was replaced by glycine in some of the samples to investigate if the freeze drying properties of the mixtures were affected in a similar manner by glycine. The carbohydrates chosen are mannitol (crystallizing), lactose and sucrose (amorphous). The collapse temperatures were determined by freeze drying microscopy and the obtained temperatures values were confirmed in actual freeze drying (small scale) at temperatures below and above the collapse temperatures. DSC, differential scanning calorimetry, was used as an independent method to determine the collapse temperature. The cakes from the small scale freeze drying experiments were examined by SEM, scanning electron microscope, for a closer look at the inner structure. The collapse temperatures are affected by the weight ratio, both for protein and glycine formulations even if they have the opposite effect. In glycine formulations a higher ratio of glycine:carbohydrate resulted in a decrease of the collapse temperature and in the protein formulations a higher ratio of protein:carbohydrate caused an increase in the collapse temperature. It seems as though glycine has the opposite effect on the collapse temperature of a carbohydrate formulation compared to the protein. The DSC results seem to support the freeze drying microscopy observations for most of the formulations. In the formulations containing mannitol collapse temperatures were difficult to determine. The dependency of weight ratio on the collapse temperature is indisputable even though protein and glycine have opposite effects. This means that glycine can not be used as a substitute for the protein in freeze drying characterization of protein formulations. Further research must be done before any conclusions regarding this difference can be drawn. Mannitol provides the best cake stability during freeze drying probably due to its crystallizing properties, but one drawback is that it is difficult to determine the collapse temperature and Tg´ for mannitol formulations by freeze drying microscopy and DSC. With lactose and sucrose it’s easier to receive unambiguous determinations of collapse temperatures and Tg´ but lactose is more sensitive to drying temperature during freeze-drying compared to mannitol. Lactose also exhibits microcollapse when freeze-dried close to the collapse temperature (* -30*C).

Place, publisher, year, edition, pages
2000. , 33 p.
Identifiers
URN: urn:nbn:se:kau:diva-52402Local ID: KEM-10OAI: oai:DiVA.org:kau-52402DiVA: diva2:1100928
Subject / course
Chemistry
Available from: 2017-05-29 Created: 2017-05-29

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