ABSTRACT
Purpose
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.
Methods
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.
Results
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.
Conclusion
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.
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Abbreviations
- CI:
-
Carr index
- D50 :
-
median diameter
- DSC:
-
differential scanning calorimetry
- G′:
-
elastic modulus
- G″:
-
viscous modulus
- IQR:
-
interquartile range
- LSS:
-
lactose stock solutions
- PEO:
-
polyethylene oxide
- PPO:
-
polypropylene oxide
- PSS:
-
poloxamer stock solutions
- δ:
-
phase angle
- η*:
-
complex viscosity
- ρb :
-
bulk density
- ρt :
-
tapped density
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Cespi, M., Bonacucina, G., Casettari, L. et al. Poloxamer Thermogel Systems as Medium for Crystallization. Pharm Res 29, 818–826 (2012). https://doi.org/10.1007/s11095-011-0606-3
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DOI: https://doi.org/10.1007/s11095-011-0606-3