An isolated report describes an increase in
serum phenytoin levels attributed to the use of
tacrolimus.
Phenytoin decreased
tacrolimus levels in one case, and has been used to reduce
tacrolimus levels after an overdose. Fosphenytoin, a prodrug of
phenytoin, may interact similarly
No interaction is established, but based on the known
metabolism of these drugs it would be prudent to monitor
tacrolimus levels in a patient given
phenytoin. Similarly, based on the single case of
phenytoin toxicity, it may also be advisable to monitor
phenytoin levels.