Enhanced stability of phenylethyl resorcinol in elastic vesicular formulations

Purpose: To enhance the stability and reduce photo-degradation of phenylethyl resorcinol (PR) by elastic vesicle formation. Methods: PR solution was stored at different temperatures, pH conditions, and under protected and unprotected natural light. The color of the solution and total active content were investigated. Three types of elastic vesicles, viz, ethosomes, transfersomes and invasomes, were prepared and their sedimentation in formulations and total active content were investigated before and after storage under various conditions for 4 months. The stability of the solutions and vesicular formulations were assessed. Results: PR solution was unstable at pH 9, higher temperature (70 +/- 1 degrees C) and under natural light. The color of PR solution changed from colorless to orange tone and the PR content decreased. On the other hand, PR entrapped within ethosome, tranfersome and invasome vesicles showed better stability, color change was not observed in the formulations, and PR content remained > 90 %. Conclusion: All the vesicles display reduced degradation of PR under thermal and natural light. Thus, PR vesicular formulation enhances stability and improves the quality of the product for use in topical administration.