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The preparation of dextran microspheres in an all-aqueous system: effect of the formulation parameters on particle
R J Stenekes1, O Franssen, E M van Bommel
1Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences (UIPS), The Netherlands. R.J.H.Stenekes@far.ruu.nl
Purpose:
The purpose of this study was to investigate the effect of the formulation parameters on the characteristics of dextran-based microspheres, prepared in an all-aqueous system.
Methods:
Dextran microspheres were formed by polymerization of methacryloyl groups attached to dextran (dexMA), emulsified in an aqueous poly(ethylene glycol) (PEG) solution. DexMA/PEG/water phase diagrams were established.
Results:
The binodals in the phase diagrams shifted to higher concentrations of dextran and PEG with decreasing molecular weight of both polymers, and with increasing degree of MA substitution. The volume-number mean diameter of the microspheres, varied between 2.5 and 20 microns. For a given formulation, the particle size was independent of the PEG/dexMA volume ratio > 40 and increased for volume ratios < 40. Furthermore, larger particles were obtained with decreasing viscosity of the continuous phase and increasing viscosity of the discontinuous phase.
Conclusions:
Particle characteristics of dextran microspheres prepared in an all-aqueous system, among which the size and initial water content, can be tailored by adjusting the formulation parameters.