Mixing Procedure for Tranexamic Acid Cream: Heat Sensitivity and Solubility
Question
I have the following cream formulation:
- Cera Alba (White Beeswas) 7%
- Soy Lecithin (Powder) 1%
- Safflower Seed Oil 12%
- Tranexamic Acid 3%
- DI Water 76%
- Broad Preseve™ 1%
I would like to know if the mixing procedure below is correct. If not, please recommend the correct method. I am concerned that Tranexamic Acid may degrade when exposed to heat and am unsure of its heat tolerance temperature. Therefore, I would appreciate guidance on the correct mixing method. If Tranexamic Acid powder is added in the final step after the cream texture has formed, will it dissolve?
Proposed Mixing Procedure:
- Melt ingredients together at 80°C:
- Cera Alba (White Beeswas) 7%
- Soy Lecithin (Powder) 1%
- Safflower Seed Oil 12%
- Heat DI Water to 80°C.
- Combine ingredients from step 1 and step 2.
- Wait for the mixture temperature to drop below 40°C, then add Tranexamic Acid 3% and Broad Preseve™ 1%.
Answer
Formulation Process Review
Your proposed mixing steps are generally correct and suitable for this type of formulation, especially regarding the heat-sensitive ingredients.
Here's a breakdown:
Steps 1, 2, and 3 (Heating and Combining Phases): Heating the oil phase (Beeswax, Soy Lecithin, Safflower Seed Oil) and water phase (DI Water) separately to around 80°C and then combining them is a standard method for creating stable emulsions, particularly when using waxes like Beeswax that require melting.
Step 4 (Adding Tranexamic Acid and Broad Preseve™): Adding Tranexamic Acid and the preservative (Broad Preseve™) when the mixture has cooled below 40°C is the correct approach. Tranexamic Acid is sensitive to high temperatures, and adding it at a lower temperature helps maintain its efficacy. Many preservatives also have maximum temperature limits for incorporation.
Regarding your concern about Tranexamic Acid powder dissolving when added at the end, Tranexamic Acid is water-soluble. Since your cream base contains a significant amount of water (DI Water 76%), the powder will dissolve in the water phase of the emulsion when added at temperatures below 40°C. Ensure thorough mixing to facilitate complete dissolution and even distribution throughout the cream.
Therefore, your mixing process is appropriate for this formula.
