Preparation and Evaluation of Liposomes Containing Ethanol and Propylene Glycol as Carriers for Nicotine

Nicotine is a fat-soluble substance that is easily absorbed through the skin and mucosal tissues of the human body. However, its properties, such as light exposure, heat decomposition, and volatilization, restrict its development and application in external preparations.This study focused on the preparation of stable nicotine-encapsulated ethosomes.During their preparation, two water-phase miscible osmotic promoters, ethanol and propylene glycol (PG), were added to obtain a stable transdermal delivery system. Skin nicotine delivery was enhanced through the synergistic action of osmotic promoters and phosphatidylcholine in binary ethosomes. Various characteristics of the binary ethosomes were measured, including the vesicle size, particle size distribution, and zeta potential. In order to optimize the ratio of ethanol and PG, the skin permeability test was performed on mice in vitro in a Franz diffusion cell to compare cumulative skin permeabilities. The penetration depth and fluorescence intensity of rhodamine-B-entrapped vesicles in isolated mouse skin samples were observed using laser confocal scanning microscopy.When ethanol:PG was used in a ratio of 5:5 (w/w), binary ethosomes were found to be the most stable, had the highest encapsulation rate (86.13 ± 1.40), smallest particle size (106.0 ± 11.0) nm, maximum transdermal depth (180 μm), and maximum fluorescence intensity (160 AU). Nicotineencapsulated ethosomes (ethanol: PG = 5:5, w/w) were an efficient and stable transdermal delivery system.The nicotine-encapsulated ethosomes containing ethanol and PG are considered to be safe and reliable as a transdermal administration agent, which does not irritate the skin.