Omeprazole interaction with phenytoin

Phenytoin can reach toxic levels while using Omeprazole. Omeprazole blocks the liver enzyme CYP 2C19, which slows down the elimination of Phenytoin. Toxic levels of phenytoin can cause drowsiness, visual disturbances, change in mental status, seizures, nausea, or ataxia. When a patient starts(or stops) on Omeprazole, it requires monitoring and possible adjustments in the dose of Phenytoin.