High-Throughput Screening of Potential Skin Penetration-Enhancers Using Stratum Corneum Lipid Liposomes: Preliminary Evaluation for Different Concentrations of Ethanol

Abstract

In this study, we developed a technique for high-throughput screening (HTS) of skin penetration-enhancers using stratum corneum lipid liposomes (SCLLs). A fluorescent marker, sodium fluorescein (FL), entrapped in SCLLs was prepared to provide a preliminary evaluation of the effect of different concentrations of ethanol on the disruption effect of SCLLs, which is an alternative for skin penetration-enhancing effects. In addition, SCLLs containing a fluorescent probe (DPH, TMA-DPH, or ANS) were also prepared and utilized to investigate SCLL fluidity. The results using SCLL-based techniques were compared with conventional skin permeation and skin impedance test using hairless rat skin. The obtained correlations were validated between FL leakage, SCLL fluidity with various probes, or skin impedance and increases in the skin permeation enhancement ratio (ER) of caffeine as a model penetrant. As a result, FL leakage and SCLL fluidity using ANS were considered to be good indices for the skin penetration-enhancing effect, suggesting that the action of ethanol on the SC lipid and penetration-enhancing is mainly on the polar head group of intercellular lipids. In addition, this screening method using SCLL could be utilized as an alternative HTS technique for conventional animal tests. Simultaneously, the method was found to be time-saving and sensitive compared with a direct assay using human and animal skins.

Potential of Stratum Corneum Lipid Liposomes for Screening of Chemical Skin Penetration Enhancers

“…Furthermore, it was found in our present work that the effect of CPEs on FL leakage and SCLL fluidity were dependent on the CPE concentration. 21) Similarly, in the study by Suhonen et al, 18) calcein leakage from SCLLs was concentration dependent for 1-dodecanol and concave downwards for Azone and dodecyl-2-(N,N-dimethylamino)propionate (DDAIP). Kim et al 15) also observed that the lipid phase transition temperature of SCLLs shifted progressively towards lower temperature with the increased concentration of pyrrolidone derivatives.…”

“…21) Similarly, Yoneto et al 17) found a good correlation between the enhancement of sugar molecule release from SCLLs and the enhancement factor on the lipoidal pathway of hairless rat SC in the presence of pyrrolidone derivatives. Furthermore, it was found in our present work that the effect of CPEs on FL leakage and SCLL fluidity were dependent on the CPE concentration.…”

“…Each sample was allowed to stand for 30 min at room temperature and immediately ultracentrifuged (Hitachi CS100GXL, Hitachi Koki Co., Ltd., Tokyo, Japan) at 289000×g, 4°C for 5 min according to our previous protocol. 21) The supernatant was collected to determine the amount of FL that leaked from FL-SCLLs after mixing with CPEs solution (FL leakage), using a microplate reader (Spectra Max ® M2 e , Molecular Devices, LLC., Sunnyvale, CA, U.S.A.) at excitation and emission wavelengths of 485 and 535 nm, respectively. This study was also performed using 75% ethanol and 0.1 M borate buffer to represent total and background FL leakage, respectively.…”

Molecular mechanism of the skin permeation enhancing effect of ethanol: a molecular dynamics study

“…It was shown that the ux of the drug increased with increase in ethanol concentration up to 80% ethanol volume fraction. Sakdiset et al 46 carried out permeation experiments of caffeine through skin in presence of various concentrations of ethanol aqueous solution. The enhancement ratio of caffeine ux increased $4 times with ethanol concentration of x ¼ 0.1 to x ¼ 0.7.…”

Improved skin penetration using active and passive enhancement methods

“…To overcome the barrier function of the SC, CPEs are conventional and effective approaches as they reduce skin barrier resistance and thus promote the penetration of drugs [20,21].…”