The answer to the question above is 1.3 mcg/mL. This is the level found which would make the nurse decide to have a required additional medication. Phenytoin is a common anti-seizure medication. Usually, the serum level of phenytoin is often checked in order to ensure effectiveness and safe levels. It is determined that the therapeutic level of phenytoin for adults is 10.0-20.0 mcg/mL.
