Paper Spray Mass Spectrometry for In Vivo Dermatopharmacokinetic Study of Skin Drugs by Touch Sampling

Many viscous drugs are used for the treatment of various skin disorders, but they pose a challenging task for dermatopharmacokinetic (DPK) studies by traditional analytical tools because of complicated processes and time-consuming sample pretreatment. In this work, we applied paper spray mass spectrometry (PSMS) for direct sampling and analysis of seven viscous drugs from the human skin surface. The detection precision was found in the range of 2.9%–20.7% (n = 5); limit of detection (LOD) and limit of quantitation (LOQ) were found at 0.01–0.12 μg and 0.15–0.39 μg, respectively. Moreover, acceptable matrix effect (3.9%–16.3%), accuracy (5.5%–16.6%), and recovery (73.6% - 135.2%) were obtained. Quantification of seven drugs on the skin surface was also performed with good dynamic ranges of three orders of magnitude. DPK studies of seven drugs were investigated for a long time up to 12 h, showing the kinetic curves of exponential function with good coefficients (R² > 0.9). Overall, our results show that PSMS is a powerful tool that integrates sampling, extraction, and microanalysis for DPK study.