Poloxamer Thermogel Systems as Medium for Crystallization
- 337 Downloads
To prepare a thermoreversible gel system able to work as a medium for crystallization at around 20°C, allowing easy retrieval of crystals by simply decreasing the gel temperature. Lactose was selected has model substance for crystallization.
Water solutions with different% of poloxamer 407, α-Lactose monohydrate, and ethanol were prepared and analysed by rheology to understand how the different components alter the gelling temperature. The systems with the required characteristics for lactose crystallization were prepared and the crystals recovered by cooling and then filtering the dispersion.
Rheological analysis showed interaction between the poloxamer and lactose. Increasing the quantity of poloxamer or lactose lowered the gelation temperature while the addition of small amounts of ethanol had a modest effect on the same property. These data were used to identify the ideal concentration of the components in order to prepare a system matching the features of our purpose. Such system yielded high quality crystals, with well-defined geometry and narrow particle size distribution.
Poloxamer is a very interesting polymer in that it is able to generate a reversible gelling medium from which crystals can be harvested by filtering, without the addition of any chemicals to promote the sol–gel transition.
KEY WORDScrystallization lactose poloxamer rheology thermogel
differential scanning calorimetry
lactose stock solutions
poloxamer stock solutions
- 2.Liesegang RE. Phot Archiv. 1896;21:221.Google Scholar
- 14.BASF Aktiengesellschaft. Poloxamer 407-Thickening agent and gel former for the pharmaceutical industry, 2005, pp. 1–8.Google Scholar
- 15.Beddow J, Meloy T. Testing and characterization of powders and fine particles. London: Heyden & Son Ltd; 1980.Google Scholar
- 16.Carr RL. Evaluating flow properties of solids. Chem Eng. 1965;72:163–8.Google Scholar
- 19.Microcal. OriginPro 8 SR1 manual software, 2007.Google Scholar
- 23.Wade A, Weller PJ. Handbook of pharmaceutical excipients. Washington DC: American Pharmaceutical Association; 1994.Google Scholar
- 25.Ford LJ, Timmins P. Pharmaceutical thermal analysis, techniques and application. Chichester: Ellis Horwood Limited; 1989.Google Scholar
- 27.Walstra P, Jenness R, Badings HT. Dairy chemistry and physics. New York: Wilkey; 1984.Google Scholar