Urea Cream Formulation and Stability for Cracked Heels

Question

Urea Cream Formulation for Cracked Heels

I would like a simple formula for a Urea cream for cracked heels. The formula should include:

Urea 20% - 30% (Note: Urea concentration over 20% is not for facial use)
Propylene Glycol 5-10%
Emollient such as LipidSoft, LipidSoft Lite, LipidSoft Palm 10%
Light Cream Maker or Pro Polymer 1-1.5%
pH adjustment using Natural PHA (Gluconolactone) to help exfoliate skin and maintain stable pH (use at a rate that adjusts the formula pH to 4-5)
Water for the remaining portion

Please elaborate on this formula, including suitable types of oil/emollient and whether adding a substance to stabilize pH is necessary, especially considering the high concentration of Urea.

MySkinRecipes Expert · Accepted Answer

Urea Cream Formulation for Cracked Heels

Based on the recommended simple formula for cracked heels, here are the components and their roles:

Urea (20-30%): A key ingredient for moisturizing and exfoliating dry, thickened skin on the heels. Concentrations above 20% are effective for keratolytic action (softening and shedding hard skin).
Propylene Glycol (5-10%): Acts as a humectant to attract and retain moisture in the skin, and also helps dissolve other ingredients.
Emollient (e.g., LipidSoft, LipidSoft Lite, LipidSoft Palm) (10%): These ingredients provide softness and smoothness to the skin. For a foot cream, options like LipidSoft Palm are suitable for providing good moisture, while LipidSoft Lite offers a lighter, non-greasy feel. You can choose based on the desired texture and feel.
Light Cream Maker™ or Pro Polymer™ (1-1.5%): These are emulsifiers and thickeners that help create the cream texture and keep the oil and water phases mixed.
Natural PHA (Gluconolactone): Used to adjust and stabilize the pH of the formula. Urea can cause the pH to rise over time, especially at higher temperatures. Gluconolactone helps keep the pH in the desired range (4-5.5) for stability and also provides a gentle exfoliating effect.
Water (Remaining portion): The base of the cream.

Regarding suitable oils:

The formula suggests using emollients from the LipidSoft range. LipidSoft Palm is a good choice for dry skin as it provides good moisturizing properties. LipidSoft Lite is a lighter option that is non-greasy and doesn't clog pores, which might be preferred for a less heavy feel. Other LipidSoft types like LipidSoft C1215 also provide softness and smoothness.

Regarding pH stabilization:

Yes, it is necessary to add a substance to stabilize the pH when using Urea, especially at higher concentrations (above 5%). Urea can decompose over time, causing the pH of the formula to increase, which can affect stability and performance. Natural PHA (Gluconolactone) is recommended in this formula and product descriptions for this purpose. It helps control the pH within the optimal range (4-5.5) for Urea stability and also contributes to the exfoliating effect on cracked heels. The recommended ratio is about 15% of the Urea concentration (e.g., if using 10% Urea, use 1.5% Gluconolactone).