Serum formulation for dark spots/melasma: Incorporating 4-butylresorcinol

Regarding your serum formula for reducing dark spots and melasma:

The selection of active ingredients like Niacinamide, N-Acetyl-D Glucosamine, 4-butylresorcinol, and Tranexamic Acid is excellent for targeting hyperpigmentation.

However, as the staff mentioned, 4-butylresorcinol is oil-soluble. Your current formula appears to be primarily water-based.

To properly incorporate 4-butylresorcinol and ensure its effectiveness and stability, you will need to either:

• Add an oil phase (around 3-5% as suggested) to the formula.
• Use a suitable solubilizer to disperse the 4-butylresorcinol in the water phase.

The percentages of the active ingredients you've chosen seem appropriate for their intended effects.

Please also double-check the recommended usage rates for all ingredients, especially the thickener (Acrylates/C10-30 Alkyl Acrylate Crosspolymer) and preservative (NaturePreserve™), to ensure they are within the manufacturer's guidelines for optimal performance and stability.

With the necessary adjustment to incorporate the 4-butylresorcinol, this formula has good potential for addressing dark spots and melasma.