FOLATES AND PHENYTOIN
If folic acid supplements are given to treat folate deficiency, which can be caused by the use of phenytoin, the serum phenytoin levels may fall, leading to decreased seizure control in some patients. Reductions in serum phenytoin levels of 16 to 50% have been described with folic acid doses between 5 mg and 15 mg; doses as low as folic acid 1 mg may interact.
Monitor phenytoin levels and adjust the dose accordingly. Fosphenytoin is a prodrug of phenytoin. Although it does not appear to have been studied, it may interact similarly.
Monitor phenytoin levels and adjust the dose accordingly. Fosphenytoin is a prodrug of phenytoin. Although it does not appear to have been studied, it may interact similarly.