What it means
phenytoinFEN-ih-toynAn anticonvulsant drug, given by mouth or IV, used to prevent and stop seizures.Full entry has a narrow therapeutic range, and small dose changes can cause big changes in the level. Most of it is bound to albumin, and only the free part works, so a low albumin (in malnutrition, older age, kidney or liver disease) can cause toxicity even with a normal total level; a free phenytoin level may then be ordered. Signs of a high level include nystagmus (jerky eye movements), unsteady walking, slurred speech, drowsiness and confusion.
For the nurse
Draw trough levels before the next dose. Teach the client not to switch brands or stop the drug suddenly, which can bring on seizures, and to keep up good mouth care, since it can overgrow the gums.
At a glance
| Normal range | Total phenytoin 10–20 mcg/mL [40–79 µmol/L]; free phenytoin 1–2 mcg/mL [4–8 µmol/L]. |
|---|---|
| Also written | serum phenytoin level, Dilantin level |
Related terms
seizure
A sudden burst of abnormal electrical activity in the brain that changes movement, feeling, behavior or awareness.
albumin
The main protein in blood plasma, made by the liver, which holds fluid inside the blood vessels and carries drugs and hormones.
phenytoin
An anticonvulsant drug, given by mouth or IV, used to prevent and stop seizures.