Adjusting Gel Formulation: Solubility and Color Issues

Question

I am adjusting a gel formulation. I plan to add Licorice Extract and Vitamin B12, reducing the water percentage accordingly to keep the total at 100%. I also want to add 3% Tranexamic Acid and reduce the water by another 3%.

1. Is my method of adjusting the water percentage correct when adding these ingredients?
2. Will adding these ingredients cause any issues in the gel formulation, particularly regarding Allantoin (currently at 0.40%) and the color from Vitamin B12 (at 2%)? My formula also contains Vitamin B5.

MySkinRecipes Expert · Accepted Answer

Subject: Re: Please review the formula

Hello,

Regarding your formula adjustments and questions:

Formula Modification (Adding Licorice and VB12, reducing water): Yes, your method of adding ingredients and reducing the water percentage accordingly to keep the total at 100% is correct in principle.
Adding Tranexamic Acid 3%: Correct, if you add 3% Tranexamic Acid, you should reduce the water percentage by 3% to maintain the total formula at 100%.

However, please consider the points raised by C7:

Allantoin Solubility: As C7 mentioned, if you significantly reduce the water content, Allantoin (at 0.40%) might precipitate, especially when the product is refrigerated. Allantoin's maximum solubility is around 0.5% of the water content in the formula. In your current formula (with Licorice and VB12 added), the water is 85.70%. 0.5% of 85.70% is about 0.4285%. Your 0.40% Allantoin is just within this limit. If you reduce water further by 3% (to 82.70%), the limit becomes 0.5% of 82.70%, which is about 0.4135%. While 0.40% is still technically below this, significant water reduction overall increases the risk of precipitation.
Vitamin B12 Color: C7 noted that 2% Vitamin B12 will likely give the gel a strong red color, which might be aesthetically unappealing.
Suggestion for Vitamin B3: C7 suggested adding Vitamin B3 (Niacinamide) at around 3%. Vitamin B3 works well with Vitamin B5 and B12 and also provides whitening benefits, complementing the Tranexamic Acid, and helps condition the skin.

In summary, your approach to adjusting percentages is correct. Just be mindful of the potential issues with Allantoin solubility at lower water levels and the color impact of Vitamin B12, as highlighted by C7. Adding Vitamin B3 is a good suggestion for enhanced benefits.