OBJECTIVE: To explore the influencing factors of drug concentration/dose ratio（ C/D） in patients with depression after taking sertraline

so as to provide reference for the clinical individualized medication of sertraline.METHODS: Retrospective analysis was performed on 529 drug concentration monitoring data from 373 patients with depression who received sertraline therapy monitoring in the Affiliated Brain Hospital of Guangzhou Medical University from 2019 to 2020. Data such as gender

age

body mass index（ BMI）

frequency of administration and drug combination were entered into the table. SPSS 23. 0 software was used for statistical analysis of the above data.RESULTS: BMI and administration frequency had significant effects on C/D of sertraline（ P < 0. 05）. The C/D of sertraline in the combined olanzapine group was significantly higher than that in the non-olanzapine group（ P < 0. 05）.The C/D of sertraline in the combined lithium group was significantly higher than that in the non-lithium group（ P <0. 01）

the differences were statistically significant. In the multiple linear regression analysis model

the effects of dose

frequency of administration and drug combination of olanzapine or lithium on blood concentration of sertraline were statistically significant. CONCLUSIONS: The influencing factors of blood concentration of sertraline are complex and have a great relationship with the dosage. The results of this study suggest that the drug combination of olanzapine or lithium may require dose adjustment of sertraline.