Topical drug delivery and the role of excipients

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PARTICULAR ASPECTS OF EXCIPIENTS FOR TOPICAL DRUG FORMULATIONS
Across dosage forms and routes of administration, it is now generally accepted that excipients cannot be regarded simply as inert or inactive ingredients. A detailed knowledge about these materials is essential for efficient and successful drug product development (1). Excipients are substances other than the API (active pharmaceutical ingredient) that are intentionally included in a drug delivery system. Excipients are similarly strictly regulated as APIs. They can only be used if appropriately evaluated for safety and released according to the requirements of GMP. Some of their general functions in medicinal products include supporting formulatability and processability, contributing to or improving stability of the API, ensuring bioavailability, and supporting compliance by patient friendly dosage forms.