Formulations with Azelaic Acid

Clear Translucent Products with Azelaic Acid

Use azelaic acid in the water phase of emulsions  with carbomers, cellulose ethers or polysaccharides such as xanthan gum or sclerotium gum.

However, these gels to be stable and clear enough, need a pH from neutral (close to 7) to slight alkaline 7.2-7.5).

For serum and gel based on high content of organic solvents such as ethanol, glycols, the pH value Is not an important parameter as the water content is low.

The solubility of azelaic acid in ethoxydiglycol is 360 g/l. A clear solution will be obtained that will not show crystallisation. Ethoxy-diglycol is mixable with water in any proportion, and also soluble in many polar lipids.

In this formula, the ethoxydiglycol is swiftly absorbed through the skin. This results in quick delivery of azelaic acid to the target location, such as in the hair follicles for the treatment of acne vulgaris.

The preparation is very low viscous, but can effectively be converted into a transparent transdermal gel using hydroxypropylcel-lulose (HPC). For serum preparations 1-2% HPC is required, depending on the desired viscosity. For gel preparations 2-4% is needed. As an alternative for ethoxydiglycol butoxydiglycol may also be used although the solubility of azelaic acid is less, estimated at 15%.

For personal care & cosmetic products both ethoxydiglycol and butoxydiglycol are limited in use because of their extreme penetra-tion power. According to EU Regulation 1223/2009 the maximum allowed concentration ethoxydiglycol in leave-on products is 2,6% while for butoxydiglycol 9,0% is allowed. These concentration limitations are not applicable for medical devices and pharmaceutical products. Taking the risk of stating the obvious, anti-acne preparations, anti-rosacea preparations and products for the treatment of alopecia areata or hair growth products are not covered by EU Regulation 1223/2009.[1]

[1] Azeco Cosmeceuticals Essential Guide, Azeco Cosmeceuticals BV, The Netherlands www.azeco-cosmeceuticals.com