Rutin-enabled Improved Systemic Exposure of Doxorubicin via Nanostructured Lipid Carriers: A proof of concept through novel LC-MS/MS analysis

ObjectiveThe objective of this study was to develop and validate a sensitive LC–MS/MS method for simultaneous quantification of doxorubicin (DOX) and rutin (RUT) in plasma and to apply it as a proof-of-concept to investigate rutin-enabled enhancement of systemic DOX exposure via nanostructured lipid carriers (NLCs).SignificancePoor oral bioavailability and dose-limiting toxicity restrict the clinical utility of DOX. Co-delivery with RUT, a bioactive flavonoid known to improve drug absorption and therapeutic response, may overcome these limitations. A robust bioanalytical strategy is essential to evaluate such combination-based nanotherapeutic systems.MethodsA simultaneous LC–MS/MS method was developed and validated in rat plasma in accordance with ICH guidelines. Dual drug-loaded NLCs were prepared using an emulsification-sonication technique and optimized through a Quality-by-Design approach. The optimized NLCs were characterized for particle size, polydispersity index and zeta potential. In vitro cytotoxicity was evaluated in MDA-MB-231 breast cancer cells, followed by pharmacokinetic studies in rats.ResultsThe validated method demonstrated excellent linearity, accuracy, precision, recovery, minimal matrix effects, absence of carryover, acceptable stability and robustness. Optimized NLCs exhibited a particle size of 171.27 ± 0.45 nm, a PDI of 0.28 ± 0.01, and a zeta potential of −23.53 ± 0.38 mV. Combination delivery of DOX and RUT resulted in a two-fold reduction in IC50 values compared with individual drugs. Pharmacokinetic analysis revealed a nearly three-fold increase in DOX AUC0–t compared with free DOX.ConclusionRutin-enabled NLCs significantly enhance the systemic exposure and therapeutic performance of DOX, validated through a novel simultaneous LC–MS/MS bio-analytical approach.