There are a number of case reports of patients taking
phenytoin who developed
toxicity when
ticlopidine was added.
Ticlopidine appears to inhibit
phenytoin metabolism. Fosphenytoin, a prodrug of
phenytoin, may interact similarly.
It would be prudent to monitor
serum phenytoin levels if
ticlopidine is added. Warn the patient to monitor for indicators of
phenytoin toxicity (blurred vision, nystagmus, ataxia or drowsiness).