Polymeric micelles of PEG-PE as carriers of all-trans retinoic acid for stability improvement

Abstract

The topical application of all-trans retinoic acid (ATRA) is an effective treatment for several skin disorders, including photo-aging. Unfortunately, ATRA is susceptible to light, heat, and oxidizing agents. Thus, this study aimed to investigate the ability of polymeric micelles prepared from polyethylene glycol conjugated phosphatidylethanolamine (PEG-PE) to stabilize ATRA under various storage conditions. ATRA entrapped in polymeric micelles with various PEG and PE structures was prepared. The critical micelle concentrations were 97-243 μM, depending on the structures of the PEG and PE molecules. All of the micelles had particle diameters of 6-20 nm and neutral charges. The highest entrapment efficiency (82.7%) of the tested micelles was exhibited by ATRA in PEG with a molecular weight of 750 Da conjugated to dipalmitoyl phosphatidylethanolamine (PEG750-DPPE) micelles. The PEG750-DPPE micelle could significantly retard ATRA oxidation compared to ATRA in 75% methanol/HBS solution. Up to 87% of ATRA remained in the PEG750-DPPE micelle solution after storage in ambient air for 28 days. This result suggests that PEG750-DPPE micelle can improve ATRA stability. Therefore, ATRA in PEG750-DPPE micelle is an interesting alternative structure for the development of cosmeceutical formulations. © 2012 American Association of Pharmaceutical Scientists.