The third-generation epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs), osimertinib, aumolertinib, and furmonertinib represent a new treatment option for patients with EGFR p.Thr790 Met (T790 M)-mutated non-small cell lung cancer (NSCLC). Currently, there are no studies reporting the simultaneous quantification of these three drugs. A simple ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the simultaneous quantitative determination of osimertinib, aumolertinib, and furmonertinib concentrations in human plasma, and it was applied for therapeutic drug monitoring (TDM). Plasma samples were processed using the protein precipitation method (acetonitrile). A positive ion monitoring mode was used for detecting analytes. D₃-Sorafenib was utilized as the internal standard (IS), and the mobile phases were acetonitrile (containing 0.1% formic acid) and water with gradient elution on an XSelect HSS XP column (2.1 mm × 100.0 mm, 2.5 µm, Waters, Milford, MA, USA) at a flow rate of 0.5 mL·min⁻¹. The method’s selectivity, precision (coefficient of variation of intra-day and inter-day ≤ 6.1%), accuracy (95.8–105.2%), matrix effect (92.3–106.0%), extraction recovery, and stability results were acceptable according to the guidelines. The linear ranges were 5–500 ng·mL⁻¹, 2–500 ng·mL⁻¹, and 0.5–200 ng·mL⁻¹ for osimertinib, aumolertinib, and furmonertinib, respectively. The results show that the method was sensitive, reliable, and simple and that it could be successfully applied to simultaneously determine the osimertinib, aumolertinib, and furmonertinib blood concentrations in patients. These findings support using the method for TDM, potentially reducing the incidence of dosing blindness and adverse effects due to empirical dosing and inter-patient differences.

Osimertinib, a new-generation inhibitor of the epidermal growth factor, has been used for the clinical treatment of advanced T790M mutation-positive tumors. In this research, an original analysis method was established for the quantification of osimertinib by ultra-performance liquid chromatography with time of flight mass spectrometry (UPLC-TOF-MS) in rat plasma. After protein precipitation with acetonitrile and sorafinib (internal standard, IS), they were chromatographed through a Waters XTerra MS C₁₈ column. The mobile phase was acetonitrile and water (including 0.1% ammonia). The relative standard deviation (RSD) of the intra- and inter-day results ranged from 5.38 to 9.76% and from 6.02 to 9.46%, respectively, and the extraction recovery and matrix effects were calculated to range from 84.31 to 96.14% and from 91.46 to 97.18%, respectively. The results illustrated that the analysis method had sufficient specificity, accuracy and precision. Meanwhile, the UPLC-TOF-MS method for osimertinib was successfully applied into the pharmacokinetics of SD rats.

Herein, the effect of silymarin pretreatment on the pharmacokinetics of simvastatin in rats was evaluated. To ensure the accuracy of the results, a rapid and sensitive UPLC–MS/MS method was established for simultaneous quantification of simvastatin (SV) and its active metabolite simvastatin acid (SVA). This method was applied for studying the pharmacokinetic interactions in rats after oral co-administration of silymarin (45 mg/kg) and different concentrations of SV. The major pharmacokinetic parameters, including Cmax, tmax, t_1/2, mean residence time (MRT), elimination rate constant (λz) and area under the concentration-time curve (AUC_0–12h), were calculated using the non-compartmental model. The results showed that the co-administration of silymarin and SV significantly increased the Cmax and AUC_0–12h of SVA compared with SV alone, while there was no significant difference with regards to Tmax and t_1/2. However, SV pharmacokinetic parameters were not significantly affected by silymarin pretreatment. Therefore, these changes indicated that drug-drug interactions may occur after co-administration of silymarin and SV.