Drug concentration is measured by collecting blood, urine or saliva for laboratory testing. The drug concentration test is to collect the patient’s blood, urine or saliva and other body fluids at regular intervals during the clinical drug treatment, and to measure the drug concentration while observing the effect of the drug. It is used to study the action and transformation process of therapeutic drugs in the body, so as to adjust the drug administration program according to the therapeutic effect of the patient, thus achieving satisfactory therapeutic effect and avoiding the occurrence of adverse reactions. Among the drug concentration tests, the blood concentration test is the most common, and it is most often used to guide the treatment of antiepileptic drugs. This method can improve the efficacy and reduce the adverse effects of antiepileptic drugs. Antiepileptic drugs that require blood concentration monitoring include carbamazepine, phenytoin sodium, and sodium valproate, etc. The optimal dosing regimen should be formulated based on the blood concentration.