Formula Review: Whitening Serum for Melasma, Freckles, and Dark Spots

Your formula includes a comprehensive range of active ingredients targeting various pathways involved in hyperpigmentation, along with several soothing agents. This multi-pronged approach is generally effective for stubborn pigmentation issues like melasma.

Here are some points to consider regarding the formulation:

Potential Issues and Considerations:

1. pH Level:

   • Several key active ingredients, such as Ethyl Ascorbic Acid and Alpha Arbutin, require a specific pH range (typically 3.5-6.5) for optimal stability and efficacy.
   • Lactobionic Acid is also acidic.
   • The combination of multiple acidic ingredients will result in a low pH for the final formula. It is crucial to measure and adjust the final pH to ensure it falls within the recommended range for all sensitive actives. A pH that is too low can increase irritation, while a pH that is too high will cause degradation of ingredients like Ethyl Ascorbic Acid and Alpha Arbutin.

2. Ingredient Solubility and Mixing:

   • Some ingredients like TXC™ (Cetyl Tranexamate HCl), Pure-Glabridin™ Licorice Extract (Glabridin 90%), Glycyrrhetinic Acid, and Hi-LiconeA™ Licorice Extract (Licochalcone A 20%) are not directly soluble in water and require dissolution in glycols (Butylene Glycol, Propylene Glycol) or oil, often with the aid of heat, before being incorporated into the main water phase.
   • Hydro-White™ also requires heat (60-80°C) to dissolve in water.
   • Ensure your mixing procedure accounts for these solubility requirements to ensure all actives are properly dissolved and dispersed for maximum efficacy and formula clarity/stability.

3. Electrolyte Sensitivity of Gel Maker:

   • Your formula uses Pro Polymer™ as a gel maker. This polymer is sensitive to electrolytes, which are present in several ingredients in your formula (e.g., 4MSK, Dipotassium Glycyrrhizate, Disodium EDTA, Z-White™).
   • The presence of these electrolytes is likely to significantly reduce the viscosity provided by 1.00% Pro Polymer™, potentially resulting in a much thinner texture than intended or even compromising the gel structure.
   • To achieve a stable gel texture, you may need to increase the concentration of Pro Polymer™ (potentially to 2-3% or higher depending on the total electrolyte load) and follow the recommended mixing procedure of adding electrolyte-containing ingredients after the gel has been formed and hydrated.

4. Compatibility of Ethyl Ascorbic Acid and Z-White™:

   • The description for Ethyl Ascorbic Acid advises against using it with Zinc PCA due to potential compatibility issues. Your formula contains Z-White™ (Zinc Glycinate), which is another zinc compound.
   • While not explicitly stated as incompatible, it is advisable to perform a small-scale compatibility test with Ethyl Ascorbic Acid and Z-White™ in your base formula to check for any signs of instability (e.g., precipitation, discoloration, loss of efficacy) before making a large batch.

5. Stabilizer Choice:

   • The descriptions for Alpha Arbutin and Dipotassium Glycyrrhizate specifically recommend using ActiveProtec™ OX to help prevent discoloration due to oxidation.
   • Your formula uses ActiveProtec™ UV. While ActiveProtec™ UV provides protection against UV light and contains some antioxidant properties, ActiveProtec™ OX might offer better specific protection against the oxidation that can cause discoloration in Alpha Arpha Arbutin and Dipotassium Glycyrrhizate. Consider if ActiveProtec™ OX would be a more suitable choice for preventing color changes in this formula.

6. Potential for Irritation:

   • You have included a high concentration and variety of potent whitening actives. While you have also included several anti-irritant ingredients (Lactobionic Acid, Dipotassium Glycyrrhizate, Glycyrrhetinic Acid, Licochalcone A, Glabridin), the overall active load is high.
   • Individuals with sensitive skin may still experience some irritation. It is recommended to perform a patch test before full facial application.

7. Odor Management:

   • Sodium Metabisulfite can have a noticeable odor. The inclusion of Odor-Kill™ is a good strategy to mitigate this, as it is effective against sulfite odors. Be aware that Odor-Kill™ can also absorb fragrance if you plan to add one (not listed in your formula).

Summary:

Your formula is well-designed to target multiple aspects of hyperpigmentation and includes good anti-irritant support. The main areas to focus on are ensuring the final pH is correct and stable, carefully managing the solubility and mixing of ingredients that require glycols or heat, addressing the electrolyte sensitivity of the gel maker to achieve the desired texture, and potentially verifying the compatibility of Ethyl Ascorbic Acid and Z-White™. Considering ActiveProtec™ OX for improved color stability of certain ingredients might also be beneficial.

Remember to perform stability testing on your final formulation to ensure it remains effective and safe over time.