Azeco Cosmeceuticals

Question: • Would Azelaic solubility in propanediol 1,3 be similar to that of propylene glycol? (mar- keting constraints, limited solvents) • We are planning to experiment with solubilizing in propanediol then suspending in scle- rotium gum adjusted to 3.8 pH (as part of a combination AHA formulation) • Would this adversely affect bio-availability and/or risk crystallization? The solubility of azelaic acid in 1,2-propylene glycol (INCI: Propylene Glycol) is comparable with 1,3-propylene glycol (INCI: Propanediol). I understand where your client s coming from as 1,2- propylene glycol is from petrochemical origin and 1,3-propylene glycol is obtained by fermentation of corn sugar and has an EcoCert/Cosmos approval. Having said that, the solubility of azelaic acid in both solvents is rather limited indeed. The solubility of azelaic acid in both solvents can be greatly increased as follows: a. Add ethoxydiglycol or ethoxytriglycol to the glycols to further increase the solubility. Ethoxydiglycol is limited in concentra- tion for personal care & cosmetics by the EU Legislator; ethoxy triglycol can be used freely without concentration limitations. For the USA the FDA has not put any constraints to both solvents. b. Azelaic acid can properly be dissolved in these glycols using chitosan in a (semi)-stoichiometric quantity. Reference is made to your booklet and the publication in SPC. 2. Azelaic acid is well tolerated by sclerotium gum (Alban Muller) and vice versa. While working in an anhydrous environment there is no concern for the pH of the system. Having said that, quantitative data on the acid/base behavior in non-aqueous solvents have not been published. When following the instructions as laid down in §1 the risk of crystallization will be minimized (but not zero !), to be confirmed by a shelf life study. Usually crystallization phenomena pop up already after a few days. Answer: 1.

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