Skin irritation by topical drugs

Area of Science:

• Dermatology
• Pharmaceutics
• Cosmetic Science

Background:

• Developing effective topical drugs requires overcoming skin permeability challenges.
• Auxiliary agents are used to enhance drug penetration but can impair the skin's barrier function.
• These agents cause varying degrees of irritation and dehydration to the stratum corneum.

Purpose of the Study:

• To investigate the effects of auxiliary agents on skin permeability and barrier function.
• To understand the mechanisms by which these agents influence the stratum corneum.
• To evaluate the implications of agent-induced skin irritation on topical drug efficacy.

Main Methods:

• Review of existing literature on auxiliary agents used in topical formulations.
• Analysis of experimental data on the effects of specific agents (e.g., propylene glycol, DMSO) on skin structure.
• Discussion of the impact of irritation on the interpretation of active ingredient performance.

Main Results:

• Auxiliary agents, including glycols, emulsifiers, alcohols, and acetone, impair the skin barrier and cause dehydration.
• Propylene glycol's dehydrating effect is concentration-dependent.
• Solvents like DMSO and dimethylacetamide directly alter stratum corneum structure.
• Some topical ingredients have limited direct irritative effects on the stratum corneum.

Conclusions:

• Auxiliary agents are crucial for topical drug penetration but compromise skin barrier integrity.
• Agent-induced irritation can be misinterpreted as reduced efficacy of active ingredients, such as corticosteroids.
• A thorough risk/benefit assessment is essential when utilizing auxiliary agents in topical formulations.