Abstract: Objective To explore the relationship between plasma concentration and therapeutic efficacy of olanzapine combined with sodium valproate in patients with bipolar disorder. 
Methods A total of 100 patients with bipolar disorder were included in the study from Jul. 2020 to Jan. 2023 and divided into three groups: the olanzapine group (n=33), the sodium valproate group (n=33), the combination of olanzapine and sodium valproate group (combination group) (n=34). All three groups received corresponding treatment for seven cycles. After treatment, the plasma concentration in each group was measured, and the improvement of symptoms was evaluated using Positive and Negative Syndrome Scale (PANSS). Bech-Rafaelsen Mania Rating Scale (BRMS) and Hamilton Depression Rating Scale (HAMD) were used to evaluate the therapeutic efficacy, and a dose-response curve was drawn to measure the therapeutic efficacy of olanzapine and sodium valproate. 
Results The research results showed that for the combination group, the doses of olanzapine were (5.03±0.21) mg/d and (5.12±0.26) mg/d respectively at 15 and 30 d after treatment, and the plasma concentrations of sodium valproate were (593.02±20.28) μg/L and (612.98±21.27) μg/L, respectively. Compared with those before treatment, the blood concentration of olanzapine significantly increased at 30 d after treatment, from (27.58±1.36 ) μg/L to (29.53±1.59) μg/L, and the blood concentration of sodium valproate showed a more significant change, increasing from (53.39±5.53) μg/L to (84.96±6.59) μg/L, suggesting significant differences (P＜0.05). The combination group of olanzapine and sodium valproate showed significant improvement in both psychiatric and behavioral symptoms and efficacy compared with the olanzapine group or the sodium valproate group (P＜0.05). 
Conclusion The combination therapy of olanzapine and sodium valproate can effectively adjust the plasma concentration of patients with bipolar disorder and improve therapeutic efficacy, providing a new treatment strategy for clinical treatment of bipolar disorder. 

Key words: bipolar disorder, olanzapine, valproic acid