Evaluation of percutaneous penetration of insect repellent DEET and sunscreen oxybenzone from emulsion-based formulations

Thumbnail Image
Wang, Tao
Journal Title
Journal ISSN
Volume Title
Acta Pharmaceutica Sinica B
Insect repellent N,N-diethyl-m-toluamide (DEET) and sunscreen oxybenzone are commonly incorporated into commercially available consumer care products that are utilized to prevent vector-borne diseases and skin aging and damage. Semisolid emulsion-based formulation has been extensively selected for active repellent and sunscreen ingredients due to their excellent solubilizing properties for both lipophilic and hydrophilic components and satisfactory customer acceptance. Under the ideal use situation, an appropriate and elegant emulsion-based formulation can minimize transdermal absorption of DEET and oxybenzone and maximize their skin protection effect. The percutaneous penetration profiles of DEET and oxybenzone from several emulsion-based formulations were evaluated and compared by using the in vitro diffusion experiments in this thesis. Various parameters in the emulsion formulations, such as emulsion type, emulsifier, emollient, penetration enhancer, thickening agent, and thixotropic properties of the emulsions, could exert significant influence on percutaneous permeation of the active ingredients from the preparations. An emulsion-based preparation using the emulsifier, Emulium 22, possessed the relatively lower skin permeation of DEET and oxybenzone than other emulsion-based preparations; it was selected for the in vivo animal study. This emulsion-based formulation containing DEET and/or oxybenzone was topically applied to rats once daily for a 60-day period to investigate systemic concentration and tissue deposition of DEET, oxybenzone, and their respective metabolites. This formulation produced lower systemic absorption of DEET and oxybenzone than the commercially available products reported in a previous animal study. The concurrent application of DEET and oxybenzone in this study did not show synergistic enhancement between the two compounds in plasma. The percutaneous penetration profiles of DEET and oxybenzone from different semisolid emulsions in the in vitro diffusion experiment provided the important information in selecting the appropriate formulation of DEET and oxybenzone for topical application. The in vivo animal study identified pharmacokinetics and biodistribution characteristics of DEET and oxybenzone from the promising lab-developed emulsion. Studies are ongoing to further improve formulation characteristics so that this emulsion-based preparation could be used to minimize overall transdermal permeation of DEET and oxybenzone from topical skin application.
Permeability, Emulsion, Insect repellent, Sunscreen
Tao Wang, Donald Miller, Frank Burczynski, Xiaochen Gu, Evaluation of percutaneous permeation of repellent DEET and sunscreen oxybenzone from emulsion-based formulations in artificial membrane and human skin, Acta Pharmaceutica Sinica B 2014;4(1):43–51