Phenytoin sodium has a highly selective inhibitory effect on the motor areas of the cerebral cortex, so it is mainly believed to stabilize the function of brain cell membranes and increase the effect of intracranial inhibitory neurotransmitters, such as 5-hydroxytryptamine and gamma-aminobutyric acid, which can treat epilepsy, and it can be an anti-neuralgic, and it can also treat ectopic rhythms of the atria and ventricles, which have anti-arrhythmic effects. Phenytoin sodium tablets are mainly used for the treatment of complex seizures, and can be used for the treatment of generalized clonic seizures and persistent status epilepticus, and are used clinically for the treatment of trigeminal neuralgia and sciatica, as well as for the treatment of some premature supraventricular and ventricular beats and ventricular tachycardia. Phenytoin sodium can also be used to treat supraventricular tachycardia or ventricular tachycardia in cases of digitalis toxicity, under the guidance of a physician.