Quantification of Baricitinib and Franz diffusion study in transdermal nano-formulation by optimized and validated liquid chromatographic method

A simple, sensitive, and robust reversed-phase high-performance liquid chromatography method was developed and validated for the quantification of JAK Inhibitor (Baricitinib) in transdermal nano-formulation and its application in in-vitro Franz diffusion studies. Chromatographic separation was achieved using a polar embedded reverse stationary phase under optimized conditions with UV detection, providing adequate resolution of the analyte from formulation excipients and membrane-related interferences. The method was validated with respect to linearity, accuracy, precision, specificity, robustness, and solution stability. The developed method demonstrated a linearity over the concentration range of 5–75 µg/mL. Accuracy was evaluated by recovery yielding mean recoveries between 98 and 102% for assay and 95–105% for diffusion, demonstrating high method accuracy. Precision studies showed intra-day and inter-day % RSD values below 2%, confirming good repeatability. Specificity studies confirmed that the analyte peak was well resolved from excipients and membrane-related components, with no interference observed at the retention time of baricitinib, and peak purity assessment indicated homogeneous peak identity. Solution stability studies demonstrated that sample solutions remained stable for up to 48 h under refrigerated conditions (2–8 °C) without significant changes in chromatographic response. The validated method was successfully applied to the assay and franz diffusion study of baricitinib in transdermal nano-formulations. The assay results confirmed uniform drug content, while diffusion studies demonstrated controlled and sustained drug release over a period of 24 h. Overall, the developed RP-HPLC method is simple, precise, accurate, and robust method. It is well suited for routine quality control, and in-vitro permeation studies of baricitinib loaded transdermal drug delivery systems developed by the authors.