Gel Serum Formulation with AHA and Niacinamide: Stability and pH Challenges

Question

I am developing a gel formulation intended to contain Vitamin C (specifically L-Ascorbic Acid), Niacinamide (Vitamin B3), and Glycolic Acid (AHA). I understand there can be issues with the stability of L-Ascorbic Acid in water-based formulas and potential compatibility problems between Niacinamide and Glycolic Acid related to pH.

Could you please advise on how to formulate a stable gel containing these ingredients, addressing the challenges of Vitamin C stability and ensuring the correct pH range for both Niacinamide and Glycolic Acid effectiveness and stability?

If combining all three is problematic, what is the best approach or a suitable alternative formulation?

Desired Ingredients:
- Vitamin C (L-Ascorbic Acid)
- Niacinamide (Vitamin B3)
- Glycolic Acid (AHA)
Product Form: Gel

MySkinRecipes Expert · Accepted Answer

Revised AHA Gel Formula (without Vitamin C)

This formula focuses on the benefits of Glycolic Acid for exfoliation and Niacinamide for skin barrier support and brightening, while addressing the stability concerns.

Water: 93.5%
Pro Polymer™ (Gel Maker): 1%
Safe-B3™ (Vitamin B3, Niacinamide): 1%
Glycopure™ (Glycolic Acid (AHA) 100% Powder): 3%
Phenoxyethanol (Extra Pure): 1%
Triethanolamine 99%: 0.5% (Approximate amount for pH adjustment - adjust as needed)

Total: 100%

Note: The amount of Triethanolamine 99% is an estimate. You will need to add it gradually while measuring the pH to reach the target range of pH 3.5-4.0.

Method for Making the Gel

Prepare the Water Phase: Measure out the water.
Disperse Polymer: Slowly sprinkle the Pro Polymer™ into the water while stirring continuously. Stir gently until the polymer is fully dispersed. Let it sit for some time (e.g., 30-60 minutes or even longer, as per product instructions) to hydrate fully and start forming a gel. Avoid high-speed mixing, which can damage the polymer structure.
Add Water-Soluble Ingredients: Once the polymer is hydrated and a basic gel structure has formed, add the Safe-B3™ (Niacinamide) and Phenoxyethanol (Extra Pure) to the mixture. Stir gently until they are completely dissolved.
Prepare Glycolic Acid Solution: In a separate small container, measure out the Glycopure™ (Glycolic Acid) powder. Add a very small amount of water (taken from the total water amount) to dissolve the powder. Stir until fully dissolved.
Combine Phases: Slowly add the dissolved Glycolic Acid solution to the main gel mixture while stirring.
Measure pH: Use a pH meter or pH strips to measure the pH of the mixture. It will be quite low due to the Glycolic Acid.
Adjust pH: Add Triethanolamine 99% drop by drop, stirring well after each addition. Continuously measure the pH as you add the Triethanolamine. Stop adding when the pH reaches your target range of 3.5-4.0. This step is crucial for the stability of Niacinamide and the effectiveness of Glycolic Acid.
Final Check: Once the desired pH is achieved and stable, give the gel a final gentle stir. Package the gel in a suitable container.

Remember to always wear appropriate personal protective equipment (gloves, eye protection) when working with cosmetic ingredients, especially acids and bases. It is also highly recommended to perform a small test batch first before making a larger quantity.

The products used in this revised formula are: