Penetration Enhancement Ranking for Tranexamic Acid in O/W Emulsion

Based on the information provided from the fact sheet and the staff's response, here is a summary of the suitability of the listed penetration enhancers for Tranexamic Acid in an O/W emulsion:

The staff ranked the penetration enhancement ability for Tranexamic Acid from most to least effective as follows:

• PE-1 Aqua
• 1,2-Hexanediol
• Butylene Glycol and Propylene Glycol (with similar ability)

Therefore, PE-1 Aqua and 1,2-Hexanediol are indicated as having better penetration enhancement capabilities for Tranexamic Acid compared to Butylene Glycol and Propylene Glycol.

However, as the staff noted, the best choice also depends on other factors of your formulation. For example, PE-1 Aqua is an oil with a slight odor, which might not be suitable for all types of O/W emulsions depending on the desired texture and scent profile.

In summary, for maximizing the penetration of Tranexamic Acid, PE-1 Aqua and 1,2-Hexanediol are generally more effective options among the ones you listed. Consider the specific characteristics of each ingredient and your overall formulation goals when making your final selection.