HM30181 mesylate is primarily used as a P-glycoprotein (P-gp) inhibitor to enhance the oral bioavailability of certain drugs. It is often co-administered with chemotherapy agents that are substrates of P-gp, such as paclitaxel, to improve their absorption and effectiveness. By inhibiting P-gp, it prevents the efflux of these drugs from the gastrointestinal tract, allowing for higher concentrations to enter the bloodstream. This application is particularly valuable in cancer therapy, where it helps to maximize the therapeutic impact of orally administered anticancer drugs, potentially reducing the need for intravenous administration and improving patient convenience.