OBJECTIVE: To investigate the characteristics of steady-state blood concentration of sodium valproate in children with epilepsy of different ages and its correlation with epileptic control and adverse drug reactions（ ADR）based on the significantly age-dependent developmental characteristic of the metabolic process of valproate

so as to obtain the safety and efficacy data of sodium valproate in pediatrics. METHODS: A total of 748 children diagnosed with epilepsy and treated with sodium valproate in the department of neurology in this hospital from Jan. 2017 to Jun.2020 were included. The early morning fasting venous blood was collected 3 d after the oral administration

the concentration of sodium valproate in the plasma was measured

and the frequency of epilepsy

nervous system reaction

gastrointestinal reaction and ADR of skin were recorded. RESULTS: The steady-state blood concentration of valproate showed a significant stepwise increase with age

and the mean blood concentration of valproate was（ 50. 06±28. 18） mg/L in epilepsy children <1 year old

（ 51. 08±18. 71） mg/L in children aged from 1 to 2 years

and（ 59. 87±22. 07） mg/L in children aged from >2 to 6 years

which was significantly higher than that in the group of children aged from 1 to 2 years

the difference was statistically significant（ P<0. 05）. The mean blood concentration of valproate was（ 63. 23±26. 67） mg/L in children aged from > 6 to 14 years old

higher than that of children aged from >2 to 6 years old

but the difference was not statistically significant（ P>0. 05）

and significantly higher than that of children aged from 1 to 2 years old（ P < 0. 001） and < 1 years old（ P < 0. 01）

the differences were statistically significant. Steady-state blood concentration of sodium valproate were lower in the low-dose group [<20 mg/（ kg·d） ]than in the medium-dose[from 20 mg/（ kg·d） to 30 mg/（ kg·d） ] and high-dose group[>30 mg/（ kg·d） ]

but the blood concentration of sodium valproate in patients in the medium-dose and high-dose group did not show the dose correlation. The control rates of epilepsy in sodium valproate medium and high blood concentration group were respectively 90. 0%（ 387/430） and 91. 1%（ 41/45）

significantly higher than those in low blood concentration group70. 0%（ 191/273）

with statistically significant difference（ P < 0. 05）. A total of 39 ADR cases were collected

and the most common ADR cases were neurological reactions（ 14 cases）

impaired liver function（ 11 cases） and digestive reactions（ 9 cases）. The incidence of ADR tended to increase with increasing blood concentration of sodium valproate and showed an age correlation

and the incidence of ADR was significantly higher in children with epilepsy in the younger age group ≤ 2 years old than in children with epilepsy in other age groups（ from >2 to 14 years old）.CONCLUSIONS:（ 1） The blood concentration and ADR of sodium valproate in children have age-specific distribution characteristics

and the blood concentration of infants and children（ ≤2 years old） is easily lower than the minimum therapeutic concentration

but more likely to have adverse drug reactions

which should be closely monitored in clinic.（ 2） The safety and efficacy of sodium valproate are satisfactory when the blood concentration of sodium valproate in children is controlled within the range from 50 mg/L to 100 mg/L.（ 3） Compared with adults

the incidence of liver damage in children is higher

and the monitoring of corresponding indicators of liver function should be strengthened during the administration of valproate sodium.