Solid state properties – salt selection
The vast majority of APIs exist as weak acids or weak bases. This gives the opportunity to alter the physic-chemical properties of the material by forming a salt.
Most often the goal of salt formation is to enhance dissolution rate, but sometimes it can be to enhance stability by reducing hygroscopicity of a compound.
As for different polymorphs, different salts can have very different physic-chemical properties. The selection of a suitable salt is often one of the first things to consider when developing a new chemical entity, as it can enhance the prospect of systemic exposure during clinical trials.
Salts are usually formed with acceptable co-formers (acids or bases) that have been used previously in marketed products intended for the same route of administration.
Consultancy is available for
• selecting the most appropriate salt screening strategy
• outsource company selection and management
• data interpretation
The goal is to fit the salt selection strategy into the overall product development strategy to get the product of suitable quality in the shortest possible development time.
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