What are the key considerations in choosing excipients for topical formulations?

Topical products are usually semi-solid in nature and typically contain more types of excipient than other types of drug products. Many of these excipients can, if used inappropriately, adversely affect the process used to manufacture the product.

In this whitepaper, we review the effect of excipient choice on the process of manufacturing topical products. The effect of the following excipient types will be discussed: surface active agents, preservatives, polymer choice and skin penetration enhancers.

Along with excipient selection, process understanding will have an impact on the success of commercial manufacturing. When scaling up a topical product manufacturing process from bench or pilot scale in preparation for process qualification, there are opportunities to maximize process understanding and optimization with a limited number of batches or trials.

Considerations include the following:

  • Understanding equipment differences and their potential impact on the process

  • Extensive sampling throughout each unit operation to understand process parameters and process efficiency

  • Performing key tests on the spot to understand required duration for individual process steps

  • Designing the testing plan to balance testing resource with knowledge benefit

  • Process stretching studies on key process parameters