OBJECTIVE: To investigate the influencing factors of serum concentration to dose ratio（C/D） of escitalopram in inpatients

so as to provide basis for clinical rational drug use. METHODS: Monitoring data of serum concentration from 275 inpatients treated with escitalopram from Oct. 2019 to Nov. 2021 were collected and retrospectively analyzed by using SPSS 25.0 statistical software. RESULTS: According to multiple linear regression analysis

only metabolism type of metabolic enzyme CYP2 C19 and daily dose could explain the significant changes in the serum concentration of escitalopram. The C/D of escitalopram in inpatients was significantly higher in the female group than in the male group（P=0.021<0.05）. In terms of drug combination

significant differences in the C/D were detected between the groups of escitalopram combined with risperidone and combined with clozapine（P=0.035<0.05）

escitalopram combined with propranolol and combined with omeprazole（P=0.030<0.05）

and escitalopram combined with propranolol and combined with clozapine（P=0.021<0.05）. Moreover

there were statistically significant differences in C/D values among the slow

fast and intermediate metabolism types of metabolic enzyme CYP2 C19（P<0.05）. Other factors such as age

manufacturer

other drug combination and metabolic enzyme CYP2 D6

had no relation with the C/D value of escitalopram（P>0.05）. CONCLUSIONS: The C/D value of escitalopram is related to gender

partial drug combination and CYP2 C19 genotyping

and clinical monitoring of therapeutic drugs can be enhanced to optimize dosing regimens in combination with blood levels

genotyping

clinical outcomes and pharmacoeconomics