Transdermal Delivery of Compounds with Different Lipophilicity and Molecular Weight from W/O Microemulsions Analyzed by UPLC-QTOF/ MS and LC-MS/MS.

Abstract

The aim of this study was to develop a novel W/O microemulsion for a natural extract of Wen-Luo-Tong (WLT) containing mainly icariin, hydroxysafflor yellow A (HSYA) and gallic acid to be applied to skin as a potential treatment for peripheral neuropathy. The oil phase was selected on the basis of affinity with the surfactant and co-surfactant. Pseudo-ternary diagrams were constructed to optimize microemulsions and finally stability studies were performed on the selected formulations. Droplet sizes were analyzed by using a zetasizer and were found to be within the desired range. Selected microemulsions with acceptable viscosities, containing 5%, 8% and 10% of water extract solution, were used for in vitro skin penetration studies using Franz diffusion cells and excised rat skin. New LC-MS/MS and UPLC-Q-TOF/MS methods were employed for quantitative and qualitative analysis. The optimized formulation (ME-4) consisting of 10% (w/w) water extract solution, 60% isopropyl myristate, 30%(w/w) Smix: Propylene glycol (5:2) significantly increased the cumulative permeated amounts of HSYA, icariin and gallic acid compared with the water extract solution controls. This novel formulation also increased the number of components penetrating rat skin. Ten components were detected in the Franz cell receptor solution using a UPLC-Q-TOF/MS system after the application of formulation ME-4 for 24h on the skin in vitro. However, only one component was detected after applying the control. Therefore, the microemulsion ME-4 was selected for future in vivo pharmacodynamic studies.