Analysis of Influencing Factors on the Steady-State Concentration/Dose Ratio of Vortioxetine Based on Therapeutic Drug Monitoring

To investigate the influencing factors of the steady-state concentration/dose ratio (C/D) of vortioxetine and promote individualized and rational use of vortioxetine. All inpatients who received therapeutic drug monitoring (TDM) of vortioxetine in our hospital from July 2022 to December 2025 were included. Basic information such as gender, age, body mass index (BMI), and CYP2D6 genotype, as well as drug treatment information including dosage and concomitant medications, was collected through the electronic medical record system. Data were statistically analyzed using SPSS 23.0 software. A total of 109 patients with measured steady-state blood drug concentrations were included in this study. The steady-state blood concentration of vortioxetine was 22.06(13.26, 35.34) ng·mL -1 , and the median (IQR) C/D value was 1.53(0.97,2.23) ng·mL -1 ·mg -1 ·d. The administered dose explained only 26.3% of the variability in vortioxetine plasma concentrations. Concomitant lamotrigine was associated with a lower C/D ratio in univariate analysis (P < 0.05), but this association did not remain significant in multivariate analysis (P = 0.154). There is a significant inter-individual pharmacokinetic difference in vortioxetine concentration. The potential effect of lamotrigine on vortioxetine C/D ratio requires further investigation, as the univariate finding was not confirmed in multivariate analysis. It is recommended that patients undergo routine therapeutic drug monitoring to ensure the safety and efficacy of vortioxetine use.