CALCIUM-CHANNEL BLOCKERS AND PHENYTOIN - OTHER CALCIUM-CHANNEL BLOCKERS
Phenytoin reduces the levels of verapamil and felodipine (bioavailability reduced by more than 90%). Fosphenytoin, a prodrug of phenytoin, may interact similarly.
Monitor the outcome of concurrent use, being aware that the dose of calcium- channel blocker may need to be raised. Given the size of the reductions seen it may be prudent to consider alternatives.
Monitor the outcome of concurrent use, being aware that the dose of calcium- channel blocker may need to be raised. Given the size of the reductions seen it may be prudent to consider alternatives.