Quantitative LC-MS/MS Assay for Evocalcet in Human Plasma: Comparative Pharmacokinetic Evaluation in Fasted and Fed...

A validated LC-MS/MS analytical method was established for quantifying evocalcet in human plasma, using evocalcet-d4 as the internal standard. Chromatographic separation was performed on a Thermo ODS C8 column (150 × 4.6 mm, 5 μm) with gradient elution of water and methanol, both containing 0. formic acid, as the mobile phases. Detection was carried out in positive ion mode using an electrospray ionization source. The plasma sample was spiked with an internal standard solution, followed by protein precipitation, and the resulting supernatant was injected into the LC-MS/MS system. The method, validated under ICH guidelines for quantitative biological analysis, demonstrated linearity from 1 to 1000 ng/mL (R² > 0.99) with an LLOQ of 1 ng/mL. Accuracy and precision were confirmed by recovery studies, and all other validation parameters were within acceptable limits. This validated method was successfully applied to characterize the pharmacokinetic profile of evocalcet in fasting and postprandial healthy Chinese volunteers after oral administration. Results showed significantly higher C_max and AUC values in the fasting group compared to the postprandial group, as well as delayed T_max (p < 0.01). The pharmacokinetic parameters, including C_max, T_max, t_1/2, and AUC_0-∞, were consistent with those reported in earlier studies. Moreover, hyperthyroid patients exhibited longer T_max and t_1/2, along with increased AUC_0-t and AUC_0-∞ values, compared to healthy individuals. These findings offer valuable methodological insights and pharmacokinetic data to advance clinical research on evocalcet, thereby contributing to a deeper understanding of its safety and efficacy profile.