Phenytoin sodium has a highly selective inhibitory effect on the motor areas of the cerebral cortex. Therefore, it can treat complex partial seizures, simple partial seizures, generalized tonic clonic seizures, and persistent status epilepticus. In addition, phenytoin sodium is slow to reach effective concentrations in brain tissue, so the effect can be slow to appear and requires several consecutive doses to be effective. It is also used to treat trigeminal neuralgia, sciatica, episodic chorea, seizure control disorder, myasthenia gravis, and recessive dystrophic epidermolysis bullosa. It is also used in cardiology for the treatment of supraventricular or ventricular premature beats, ventricular tachycardia, and is particularly suitable for ventricular arrhythmias in cases of cardiac glycoside intoxication, and should be used under the supervision of a physician.