Mirtazapine does not appear to affect the
pharmacokinetics of
phenytoin.
Phenytoin decreases the AUC and maximum
plasma levels of
mirtazapine by 47% and 33%, respectively. Fosphenytoin, a prodrug of
phenytoin, may interact similarly.
The
mirtazapine dose may need to be increased in the presence of
phenytoin. Monitor concurrent use to ensure
mirtazapine is effective.