Formulation guided by Hansen Solubility Parameters and realized via High Throughput Screening
By Sarah Gregory
Syntopix recently attended an Intelligent Formulation event on how to use high throughput screening to accelerate formulation development at which we presented a poster.
The poster summarises how Hansen Solubility Parameters can be used to develop topical formulations and how the process can be automated to efficiently translate concepts into prototype formulations.
Excerpts from the poster by Professor Steven Abbott, Dr. Gavin Donoghue and Dr. Anne Eady are below:
The Problem
Formulating for delivery of actives into skin requires multiple compromises. The active has to be soluble in the delivery “chassis”, and the chassis needs to solubilise the correct part of the skin in order to aid the permeation of the active. At the same time, the solvents/excipients in the chassis have to meet strict regulatory guidelines. Almost inevitably this requires a complex mixture and the solubility characteristics of the mixture need to be known in order to be optimized. Without rational formulation guidelines, this task is often hit-and-miss, using simplistic and misleading terms such as “hydrophilic” or “lipophilic”, which don’t do justice to the complexity of chemical space. Syntopix develops novel antimicrobials for the management of acne prone skin. The company was seeking a method of rational formulation design in order to ensure efficient delivery to the target site.
Understanding solubility characteristics
One proven, powerful method for understanding solubility is the use of Hansen Solubility Parameters. These 3 values provide a means of predicting whether one material will dissolve in another and form a solution:
- δD represents the energy from dispersion bonds
- δP represents the energy from dipolar intermolecular forces
- δH represents the energy from hydrogen bonds
The HSP of a mixture is simply the weighted average of the individual components. Using HSPs, it is possible to make a solvent from two non-solvents. Syntopix has exploited this approach to devise solvent mixtures for difficult to solubilise actives.
To view the full poster, please click here.
