This cream breaks after preparation: hydroquintic 4% Kojic acid 4% (depigmentating) Retinoine or tretioic acid 0.05% Cetomacrogolcreme ad 100g

Kojic acid, 5-Hydroxy-2-hydroxymethyl-4-pyrone, 5-Hydroxy-2-(hydroxymethyl)-4H-pyran-4-one
CAS #: 501-30-4

Kojic acid (C6H6O4; 5-hydroxy-2-(hydroxymethyl)-4-pyrone) is a chelation agent produced by several species of fungi, especially Aspergillus oryzae, which has the Japanese common name koji. "Kojic acid is a by-product in the fermentation process of malting rice, for use in the manufacturing of sake, the Japanese rice wine." [1] It is a mild inhibitor of the formation of pigment in plant and animal tissues, and is used in food and cosmetics to preserve or change colors of substances. It is used on cut fruits to prevent oxidative browning, in seafood to preserve pink and red colors, and in cosmetics to lighten skin. Kojic acid also has antibacterial and antifungal properties.

Kojic acid is a more recent remedy for the treatment of pigment problems and age spots. Discovered in 1989, kojic acid has a similar effect as hydroquinone. Kojic acid is derived from a fungus, and studies have shown that it is effective as a lightening agent, inhibiting production of melanin (brown pigment).

Kojic acid (5-hydroxy-2-(hydroxymethyl)-4-pyrone), a fungal metabolic product, has increasingly been used as a skin-depigmenting agent in skin care products marketed in Japan since 1988. In order to determine its frequency of sensitization, during 1 year from October 1992 to September 1993, we performed patch testing with it in 220 female patients with suspected cosmetic-related contact dermatitis. Of the 220 patients, 8 used at least 1 skin care product containing kojic acid, 5 of whom reacted to kojic acid as well as to 1 or more their own products containing 1% kojic acid, but not to their other products not containing it, and 3 of whom were negative to kojic acid and all their own products. Patch testing with kojic acid in the remaining group of 212 patients, who had not previously used skin care products containing it, was negative without exception. The 5 kojic-acid-sensitive patients, aged 34 to 58 years, developed facial dermatitis 1-12 months after starting application of kojic-acid-containing products. Kojic acid is considered to have high sensitizing potential, as a comparatively high frequency of contact sensitivity was observed in patients using products containing it (5 out of 8).

Features:

1. Skin Lightening. Kojic Acid Dipalmitate offers more efficacious skin lightening effects. Compared with kojic acid, Kojic Acid Dipalmitate markedly enhances the inhibitory effects on tyrosinase activity, which prohibits the formation of melanin.
2. Light and Heat Stability. Kojic Acid Dipalmitate is light and heat stable, while kojic acid tends to oxidize over time.
3. pH Stability: Kojic Acid Dipalmitate is stable within a wide pH range of 4-9, which provides flexibility to formulators.
4. Color Stability. Unlike kojic acid, Kojic Acid Dipalmitate does not turn brown or yellow over time for two reasons.First, kojic acid is not stable to light and heat, and tends to oxidize, which results in color change (often yellow or brown). Second, kojic acid tends to chelate with metal ions (e.g. iron), which often results in color change.On the contrary, Kojic Acid Dipalmitate is stable to pH, light, heat and oxidation, and does not complex with metal ions, which lead to color stability.

Solubility soluble in ware alcohol, mineral oil and esters.

Use level Skin care products: 1-7%

R / Hydroquinone 4% in Neostrata Pigment Lightning Gel.

The gel contains kojic acid (2%), citric acid (1%), glycolic acid (3.2%), lactic acid (0.8%), gluconolactone (5%) and vitamin C (0.5%). The concentration of vitamin C is not stated, so I don't know if there is enough Vit C present that can serve as an antioxidant for the hydroquinone. Do I have to add other antioxidants?

If tretioic acid does not occur in the composition, I think that the concentration of vitamin C is sufficient and no other antioxidant should be added. The setting of the gel is not known and, therefore, compatibility with hydroquinone must be considered.

This cream is given a shelf life of 8 weeks, stored at RT.