Understanding Encapsulated Retinoids

You have questions about the stability and usage of encapsulated retinoids. Here's some information based on your questions and product details:

1. Stability Without Stabilizers

Even when encapsulated and stored in an opaque bottle away from light at room temperature, encapsulated retinoids can still degrade over time, especially without additional stabilizers. The color change to brown you observed is a sign of this degradation.

While encapsulation provides some protection, it doesn't make the ingredient completely stable. For optimal shelf life and to minimize degradation, it is highly recommended to store encapsulated retinoids in a cool place, ideally in the refrigerator (2-8°C), and to include appropriate stabilizers in your formulation. The exact time until color change occurs without stabilizers will vary depending on the specific product, concentration, and storage conditions, but degradation is likely to happen sooner than if stabilizers are used and proper storage temperatures are maintained.

2. Oil-Free Stabilizers

You are looking for oil-free stabilizers besides Vitamin E or Protec™ products. For water-based or oil-free formulations, you can consider water-soluble antioxidants that help protect sensitive ingredients like retinoids from oxidation and degradation. Some examples include:

• Vitamin C Derivatives: Water-soluble forms like Sodium Ascorbyl Phosphate or Ascorbyl Glucoside.
• Ferulic Acid: A potent antioxidant often used in combination with Vitamins C and E, and can be used in water-based formulas.
• Certain Plant Extracts: Some plant-derived antioxidants can be water-soluble.

These ingredients can help enhance the stability of your formulation without adding oil.

3. Thai FDA Regulations for Retinoids

Regarding the maximum permitted percentage by the Thai FDA (อย.), the regulations specify limits for different forms of Vitamin A in ready-for-use cosmetic products:

• Retinol, Retinyl Acetate, and Retinyl Palmitate: The maximum permitted concentration is 0.3% (calculated as Retinol equivalent).
• Retinal (Retinaldehyde): The maximum permitted concentration is 0.05% (calculated as Retinol equivalent).
• Hydroxypinacolone Retinoate (HPR): The maximum permitted concentration is 0.3% (calculated as HPR).

It's important to note that the percentage stated on a raw material product, such as an encapsulated form, refers to the concentration of the active ingredient within that raw material. When formulating, you must calculate the final concentration of the active retinoid (Retinol, Retinal, HPR, etc.) in your finished product to ensure it complies with the specific Thai FDA limit for that particular retinoid form.

The 2% you mentioned might be a recommended usage rate for a specific encapsulated product, not the maximum permitted concentration of the active retinoid in the final cosmetic product according to FDA regulations. Always calculate the final active concentration based on the percentage of the raw material used and the percentage of the active within that raw material.