Activated Resorcinol and Ethoxydiglycol Usage

Here is information regarding your questions about Activated Resorcinol and Ethoxydiglycol:

1. Activated Resorcinol

If you added Activated Resorcinol directly to your finished cream and it dissolved completely without needing a separate solvent like LipidSoft, its quality should not degrade. The key is ensuring it is fully dissolved and evenly distributed within the formula. While pre-dissolving in an oil phase like LipidSoft is a recommended method to ensure solubility, if direct addition achieves full dissolution, it can be acceptable.

However, for optimal stability of Activated Resorcinol, it is important to maintain the formula's pH between 4.5-5.5 and include Disodium EDTA at 0.2% to help prevent discoloration. The finished product should also be protected from light, for example, by using opaque packaging, and stored away from light and humidity, ideally in a refrigerator (6-8°C) for long-term storage.

2. Ethoxydiglycol

Regarding Ethoxydiglycol, using higher concentrations within the recommended range (which is typically 1-10%, but current regulations limit usage to a maximum of 2.6% for leave-on products) does not necessarily mean better penetration. There is an optimal concentration level for each active ingredient and carrier combination that provides the best delivery into the skin.

Using too high a concentration of a carrier like Ethoxydiglycol can sometimes lead to a "reservoir" effect in the outermost layer of the skin, which can actually reduce the overall absorption into deeper skin layers. The most effective penetration occurs when the active substance is dissolved at a level close to its saturation point in the formula.

Ethoxydiglycol is a versatile solvent and carrier that is soluble in water, ethanol, glycols, and natural oils. It can often be incorporated into finished cream bases, provided it is compatible with the cream's formulation and properly mixed to ensure homogeneity.