Prediction of Skin Permeation of Flurbiprofen from Neat Ester Oils and Their O/W Emulsions

Improvement of Skin Permeation of Caffeine, a Hydrophilic Drug, by the Application of Water Droplets Provided by a Novel Humidifier Device

Recently, a novel humidifier that sprays water fine droplets equipped with a copolymer, poly(3,4-ethylene dioxythiophene)-poly(styrene sulfonate) (PEDOT/PSS) was developed. PEDOT/PSS in the humidifier absorbs water from the environment and releases fine water droplets by heating. In the present study, the effect of hydration on the skin barrier, stratum corneum, was first determined by the application of fine water droplets using the humidifier. The skin-penetration enhancement effect of a model hydrophilic drug, caffeine, was also investigated using the humidifier and compared with a conventional water-evaporative humidifier. More prolonged skin hydration effect was observed after application of the fine water droplet release humidifier using PEDOT/PSS than that using a conventional humidifier. In addition, markedly higher skin permeation of caffeine was observed in both infinite and finite dose conditions. Furthermore, higher skin permeation of caffeine from oil/water emulsion containing caffeine was observed in finite dose conditions by pretreatment with the humidifier using PEDOT/PSS. This device can provide water droplets without replenishing water, so it is more convenient for enhancing the skin permeation of chemical compounds from topical drugs and cosmetic formulations.

Development and Evaluation of Cucurbitacin B Microemulsion: the Effect of Oil Phase and Aqueous Phase on Drug Percutaneous Absorption Based on ATR-FTIR Spectroscopy and Molecular Modeling

The present study aimed to develop a cucurbitacin B microemulsion (CuB-ME) and investigate the mechanism of the enhanced drug skin absorption at the molecular level. Firstly, the pseudo-ternary phase diagrams were developed to evaluate the effect of composition on microemulsion properties systematically. The formulation composition types and ratios of oil phase, surfactant, co-surfactant, and aqueous phase were optimized by an in vitro skin permeation experiment, and the optimized formula was confirmed with the pharmacodynamics study. Furthermore, the molecular mechanism of enhanced skin permeation was investigated using ATR-FTIR and molecular modeling. As a result, the optimized CuB-ME formulation was composed of Azone:Tween 80:ethanol:water = 2.5:16.9:5.6:75.0 (w/w/w/w). The oil phase improved skin permeation by disordering the stratum corneum intercellular liquid, while the aqueous phase impacted the particle size of the microemulsion and permeability coefficient of the drug. Besides, the hydration state of skin lipid also enhanced drug permeation by the interaction of water and the polar head of ceramide. The in vitro skin permeation amount was 45.47 ± 10.39 μg/cm², and no significant skin irritation was observed. The pharmacodynamics study demonstrated that CuB-ME had a significant therapeutic effect on the animal tumor model. In conclusion, the CuB-ME was developed successfully and the effect of the oil phase and aqueous phase on drug skin permeation was clarified at the molecular level.