Preparation, Investigation of Physicochemical Properties and Stability of Azelaic Acid Gel Formulation

Rosacea as a skin inflammatory disease may be triggered by some types of bacteria. Azelaic acid with antibacterial property can be used for treatment of skin conditions such as Rosacea.

In this study, we aim to prepare and evaluate the physicochemical properties and primary stability of 15% azelaic acid gel.

For the gel preparation, first, an aqueous solution containing ethylenediaminetetraacetic and benzoic acids was prepared. Then, a mixture of polysorbate 80 and triglyceride was added to the solution at 50°C. Then, lecithin, propylene glycol, and carbomer 940 P was added to the mixture, and stirred. After that, the gel was prepared. Then, 15 g of dissolved azelaic acid in propylene glycol was added to the gel. Finally, the formulation was homogenized for 15 min.

On the day of production, all the formulations had a smooth appearance and the amount of azelaic acid was about 15%. In the preliminary stability study for 3 months, the amount of azelaic acid in the formulation 5 (F5), prepared using homogenizer, was more than 99% of drug content, without any significant difference with other formulations. The released drug from F5 was 30% in the first hour and 50% after 2 hours.

All prepared formulations have acceptable pH, viscosity, and drug content. In 3 months, the highest homogeneity of azelaic acid with the lowest standard deviation was seen in the F5 formulation, indicating the importance of using homogenizer in azelaic acid gel preparation. Also, the propylene glycol 18% w/w, in addition to having a co-solvent role, can increase the release of azelaic acid from the gel.