A dual-stage stabilized LC-MS/MS method for the quantification of ibuprofenamine in human plasma

BACKGROUND: Ibuprofenamine is a novel spray prodrug of ibuprofen designed to reduce gastrointestinal adverse effects through local administration. Its low systemic exposure and extreme susceptibility to rapid ex vivo enzymatic hydrolysis demand a highly sensitive and stabilized bioanalytical method. RESEARCH DESIGN AND METHODS: We developed an LC-MS/MS assay using simple protein precipitation. A rigorous dual-stage stabilization strategy, which employed a high-capacity NaF/citric acid buffer during blood collection and an acidic vehicle prior to plasma extraction-was implemented to completely arrest prodrug degradation. RESULTS: The method achieved a lower limit of quantification (LLOQ) of 40 pg/mL with a linear range of 40-2000 pg/mL. Intra- and inter-batch precision and accuracy were well within ±15%. The stabilization protocol extended sample stability to 120 days at -70°C, effectively eliminating ex vivo hydrolysis artifacts. CONCLUSIONS: This robust, dual-stage stabilized LC-MS/MS method effectively overcomes the bioanalytical challenges of labile ester prodrugs. It was successfully applied to support a clinical pharmacokinetic study of ibuprofenamine spray.