Depakote ER is used in the treatment of a variety if seizure disorder. Sometimes, the drug is used in conjunction with other seizure medications to achieve better results than when it is used on its own. Depakote ER is also used in the treatment of manic depression and prevents migraine headaches. It should not be used by anyone who is pregnant without an advice from the doctor. It has the ability to cause harm to the unborn child. Depakote should not be used by a patient who has a liver problem.