Oxcarbazepine Extended-Release Tablets and Phenytoin Sodium

In the database of official manuals used in the service creation an interaction registered by statistical results of studies was found, which can either lead to negative consequences for the patient health or strengthen a mutual positive effect. A doctor should be consulted to address the issue of joint drug administration.

Using phenytoin together with OXcarbazepine can alter the blood levels and effects of both medications. Specifically, phenytoin levels may increase, especially if you take more than 1200 mg of OXcarbazepine per day. At the same time, OXcarbazepine levels may decrease, which may make the medication less effective. You may need a dose adjustment or more frequent monitoring by your doctor to safely use both medications. Contact your doctor if you experience nausea, vomiting, twitching eye movements, blurred vision, slurred speech, loss of balance or coordination, tremors, sluggishness, confusion, or hallucinations, as these may be symptoms of excessive effects of phenytoin. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

MONITOR: Coadministration with oxcarbazepine may increase the plasma concentrations of phenytoin. The proposed mechanism is inhibition by oxcarbazepine and its active metabolite (10-monohydroxy derivative, or MHD) of the CYP450 2C19-mediated metabolism of phenytoin. In vivo, the plasma levels of phenytoin increased by up to 40% when oxcarbazepine was given at dosages above 1200 mg/day. Conversely, phenytoin 250 to 500 mg/day can decrease the plasma concentrations of MHD by approximately 30% due to induction of CYP450 isoenzymes. Since MHD is responsible for much of the pharmacologic effects of oxcarbazepine, the potential for altered anticonvulsant activity should be considered.

MANAGEMENT: Pharmacologic effects and serum phenytoin levels should be monitored more closely following the addition, discontinuation or change of dosage of oxcarbazepine, and the phenytoin dosage adjusted as necessary. Particular caution is advised when oxcarbazepine is administered at dosages greater than 1200 mg/day. Patients should be advised to contact their physician if they experience signs and symptoms of phenytoin toxicity such as nausea, vomiting, tremors, ataxia, lethargy, slurred speech, visual disturbances, or changes in mental status. Likewise, patients stabilized on oxcarbazepine should be monitored more closely whenever phenytoin is added to or withdrawn from therapy and during the period of phenytoin titration.

Oxcarbazepine Extended-Release Tablets

Generic Name: oxcarbazepine

Brand name: Oxtellar XR, Trileptal

Synonyms: Oxcarbazepine, OXcarbazepine

What is Oxcarbazepine Extended-Release Tablets?

Phenytoin Sodium

Generic Name: phenytoin

Brand name: Dilantin, Dilantin Infatabs, Phenytek, Phenytoin Sodium, Prompt

Synonyms: n.a.

What is Phenytoin Sodium?