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Pharmaceutical Research

, Volume 29, Issue 3, pp 818–826 | Cite as

Poloxamer Thermogel Systems as Medium for Crystallization

  • Marco Cespi
  • Giulia Bonacucina
  • Luca Casettari
  • Giovanna Mencarelli
  • Giovanni Filippo Palmieri
Research Paper

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.

KEY WORDS

crystallization lactose poloxamer rheology thermogel 

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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Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  • Marco Cespi
    • 1
  • Giulia Bonacucina
    • 1
  • Luca Casettari
    • 2
  • Giovanna Mencarelli
    • 1
  • Giovanni Filippo Palmieri
    • 1
  1. 1.University of CamerinoCamerinoItaly
  2. 2.University of UrbinoUrbinoItaly

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