Comparative tissue distribution analysis of Achyranthes bidentata Blume saponins via intragastric, intraperitoneal, and intravenous administration using simultaneous UPLC-MS/MS detection

• A simple and rapid ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method has been developed for the simultaneous determination of the distribution of five AB saponins. • The method has been validated, demonstrating high sensitivity and accuracy, and has been successfully applied to the study of AB saponins tissue distribution under different administration routes. • This study compares the distribution of AB saponins through three different administration routes (intragastric, intraperitoneal, and intravenous injection). • The research provides a theoretical basis for the improvement of AB saponins formulations, the exploration of suitable administration routes, and the enhancement of bioavailability. Saponins, the primary bioactive components of Achyranthes bidentata Blum e (AB), exhibit neuroprotective and anti-inflammatory properties. However, the lack of pharmacokinetic (PK) data, particularly on tissue distribution and first-pass effects, critically hinders their therapeutic development. Therefore, a rapid ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) method (9-min run time) was validated to simultaneously quantify five AB saponins in mice tissues (brain, heart, liver, spleen, lung, kidney; n = 5 per time point) at 10, 30, 60, 120, and 240 min post-administration. The method demonstrated excellent linearity ( R 2 > 0.99, 1–2500 ng/mL), precision (RSD ≤ 7.04%), accuracy (85%–115%), and recovery rates (86.6%–97.2%, RSD ≤ 11.39%) per ICH M10 guidelines. The results demonstrate that the saponin concentrations in various tissues after IG and IP administration were lower compared to those after IV administration, with levels reaching only 10% of the latter. Although all these compounds are pentacyclic triterpenoid saponins with an oleanane skeleton, their tissue distribution in vivo varies significantly. The elimination of achyranthoside D, ginsenoside R0, and araloside A is relatively slow in various tissues. In contrast, chikusetsusaponin IVa is rapidly eliminated from various tissues. The ability of four saponins to cross the blood-brain barrier is highly beneficial for the development of therapeutic drugs for central nervous system diseases. Additionally, the results from different administration routes indicate that AB saponins may exhibit a pronounced gastrointestinal and hepatic first-pass effect in vivo , which should be considered in future research. This study can guide multi-route study of AB saponins provides critical insights for formulation optimization and dosing regimen design to mitigate first-pass effects