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Solubility parameters as predictors of miscibility in solid dispersions.
D J Greenhalgh1, A C Williams, P Timmins
1Drug Delivery Group, Postgraduate Studies in Pharmaceutical Technology, the School of Pharmacy, University of Bradford, BD7 1DP, U.K.
Journal of Pharmaceutical Sciences
|November 17, 1999
Summary
Interactions in solid dispersions were studied using solubility parameters. Large differences in solubility parameters between drug and carrier indicate potential incompatibilities in pharmaceutical formulations.
Area of Science:
- Pharmaceutical Science
- Materials Science
Background:
- Hydrophobic drugs often exhibit poor solubility, necessitating formulation strategies like solid dispersions.
- Hydrophilic carriers are commonly used in solid dispersions to improve drug dissolution and bioavailability.
Purpose of the Study:
- To investigate drug-carrier interactions and potential incompatibilities in solid dispersions.
- To evaluate the utility of solubility parameters in predicting these interactions.
Main Methods:
- Solid dispersions of ibuprofen (hydrophobic drug) with xylitol and other hydrophilic carriers were prepared using solvent evaporation and fusion.
- Bridging agents were incorporated to assess their effect on solid dispersion formation and drug-carrier interactions.
- Hildebrand solubility parameters were used to interpret experimental results and predict incompatibilities.
Main Results:
- Ibuprofen showed no interactions with sugar carriers but interacted with bridging agents.
- Bridging agents were immiscible with xylitol in the liquid state.
- A correlation was found between large differences in solubility parameters and observed incompatibilities.
Conclusions:
- Hildebrand solubility parameters can indicate potential incompatibilities in drug-carrier systems for solid dispersions.
- Partial solubility parameters may offer more accurate predictions of interactions and incompatibilities.