Preparation and Evaluation of Pluronic Lecithin Organogels in Cosmetics SEONG JUN YANG and KYUNG-SUP YOON , Department of Chemistry & Cosmetics, Jeju National University, Jeju-do 63243, Korea (S.J.Y, K.-S.Y.) Accepted for publication March 1, 2021. Synopsis This study was performed to investigate the application of pluronic lecithin organogel (PLO gel) in cosmetics as a topical drug delivery system. PLO gel was known as transdermal drug delivery systems. It has a very interesting system, owing to their biocompatibility their amphiphilic nature, facilitating dissolution of various drug classes and their permeation enhancement properties. We realized that PLO gel has a critical shortcoming of fl owability at low temperatures to be used as a cosmetic ingredient. To improve this drawback, this study aimed to fi nd an appropriate quantity of three main compositions of PLO gel, including aqueous phase (poloxamer 407 and water), polyol phase (PEG-400), and oil phase (lecithin and oil), and applied an experimental design using the response surface methodology (RSM). We assessed the elapsed time change by temperature in each PLO gel formulation, observed the morphology of PLO gel using fi eld emission scanning electron microscope (FE-SEM), and determined the gelation point by using differential scanning calorimetry (DSC). Rheology measurements to assess viscoelastic properties were determined by using a rheometer, and skin permeation effi ciency was assessed by diffusion system. It was confi rmed that three main factors (hydrogenated lecithin, PEG-400, and poloxamer 407) of PLO gel should be balanced without fl owability even in cold temperature. Through the RSM, it was assumed that the most effective ingredient was PEG-400 at PLO gel formulation and physical properties. The PLO gel formulation (hydrogenated lecithin 5.0%, PEG-400 20.0%, and poloxamer 407 15.0%) was evaluated as the most suitable formulation for use in cosmetics due to its viscosity and elasticity results. The shape was observed through FE-SEM, and it was confi rmed that the PLO gel forms a polymeric bicontinuous microemulsion structure. Regarding the applicability of PLO gel in cosmetics, we verifi ed that PLO gel can be used in a delivery system for active substances. The study fi ndings suggest that PLO gel can be used as one of the ingredients in cosmetic formulations. INTRODUCTION Topical and transdermal drug delivery systems (TDDSs) are widely used in the fi eld of drug delivery systems (DDSs). These DDSs are most commonly designed to deliver the drugs through the skin. The skin is composed of three main layers: the epidermis, the dermis, and the subcutaneous fat tissue (1). A variety of advanced DDSs has been formu- lated to facilitate drug delivery through the epidermis and dermis, but do not allow suc- cessful drug deliver via the epidermis layer. The special characteristic of TDDSs is to Address all correspondence to Kyung-Sup Yoon at ksyoonjh@jejunu.ac.kr. J. Cosmet. Sci., 72, 325–346 (May/June 2021) 325