Mixing Glycolic Acid and Azelaic Acid into Aloe Vera Gel Base

Yes, you can mix Glycolic Acid and Azelaic Acid into the Aloe Vera Gel (Heavy) base, but you need to follow specific steps and consider the pH of the final mixture.

Mixing Order

Based on the product types and the instructions for the Aloe Vera Gel base:

1. Add the Glycolic Acid powder (5%) to the Aloe Vera Gel base at room temperature. Stir thoroughly for 3-5 minutes, let it sit for 15-30 minutes, and stir again until the powder is completely dissolved. Ensure no powder particles are visible.
2. Once the Glycolic Acid is fully dissolved and the mixture is homogeneous, add the Azelaic Acid (Liquid Azelaic™) (10%). Stir for 1-3 minutes until the liquid is evenly dispersed throughout the gel.

Important Consideration: pH

Mixing Glycolic Acid and Azelaic Acid requires careful attention to pH, as their optimal working ranges differ:

• Glycolic Acid is most effective at a low pH, ideally between 2.5 and 3.5. Its efficacy significantly decreases above pH 4.0.
• Azelaic Acid (Liquid Azelaic™), which is Potassium azeloyl diglycinate, is water-soluble and works in a pH range of 5-11. The product itself has a pH of approximately 4.5-8.

Mixing a significant amount of acidic Glycolic Acid will lower the pH of the Aloe Vera Gel base. While a low pH is good for Glycolic Acid, it might be too low for the optimal function and stability of the Azelaic Acid derivative (Liquid Azelaic™), which prefers a higher pH.

You must check the pH of your final mixture. Aim for a pH that balances the efficacy of both ingredients, although achieving the absolute optimal pH for both simultaneously might be challenging. A pH between 3.5 and 4.0 might be a reasonable compromise, allowing some efficacy for both while staying within acceptable ranges for skin application. You may need to adjust the pH using a suitable pH adjuster if necessary.

Preservative

The Aloe Vera Gel (Heavy) base already contains Phenoxyethanol as a preservative (0.40%). Phenoxyethanol is a broad-spectrum preservative effective against bacteria, yeast, and mold, typically working well in a pH range of 3-8.

Since the base already contains a preservative, you may not need to add an additional one, provided the final pH of your mixture remains within the effective range of Phenoxyethanol (ideally pH 3-8).

However, adding active ingredients can sometimes affect the efficacy of the preservative system or introduce microbial contamination. It is highly recommended to perform a challenge test on your final product to confirm that the existing preservative system is sufficient to protect the formulation from microbial growth over its shelf life.

In summary, you can mix the ingredients into the base following the powder-then-liquid order. Pay close attention to the final pH and adjust if needed to balance ingredient efficacy and ensure the base's preservative remains effective. Ideally, confirm preservation efficacy with a challenge test.