Rx Update: July 2000

Oxcarbazepine and Micromedex - Intranet Version

Mary Ross, R.Ph., M.B.A.
Peer Review Status: Internally Reviewed

Oxcarbazepine
Oxcarbazepine (Trileptal®- Novartis) is an analogue of carbamazepine (Tegretol®) that is indicated for use as monotherapy or adjunctive therapy in the treatment of partial seizures in adults. It is also indicated for use as adjunctive therapy in the treatment of partial seizures in children 4 to 16 years of age.

The most commonly observed adverse events with oxcarbazepine therapy are dizziness, somnolence, diplopia, fatigue, nausea, vomiting, ataxia, abnormal vision, tremor, dyspepsia and abnormal gait. In addition to these events, 2.5% of oxcarbazepine-treated patients developed clinically significant hyponatremia (Na+ < 125 mmol/L). Therapy with oxcarbazepine is contraindicated in patients with a known hypersensitivity to oxcarbazepine or to any of its components. It is also important to note that approximately 25 to 30% of patients who have had a hypersensitivity reaction to carbamazepine will also experience a reaction to oxcarbazepine.

Although oxcarbazepine is associated with fewer drug interactions than many other antiepileptic drugs, there are still some clinically relevant interactions. When oxcarbazepine is administered at doses greater than 1200 mg/day concomitantly with phenytoin, an increase of up to 40% in the plasma levels of phenytoin is observed. Therefore, the dose of phenytoin may have to be decreased when used concomitantly with oxcarbazepine at doses greater than 1200 mg/day. In addition, when oxcarbazepine and lamotrigine were administered concurrently, concentrations of lamotrigine were decreased 28% compared to lamotrigine monotherapy. Co-administration with oral contraceptives can result in a decrease of the plasma levels of ethinyl estradiol and levonorgestrel, resulting in decreased effectiveness of oral contraceptives.

Whether oxcarbazepine therapy is being initiated as monotherapy, adjunctive therapy, or if a patient is being switched from another antiepileptic agent, treatment is started at a dose of 300 mg twice daily, with or without food. The dose is slowly titrated upwards until the desired clinical response is observed, usually at a target maintenance dose of 1200 to 2400 mg/day. In pediatric patients 4 to 16 years of age, treatment should be initiated at a daily dose of 8 to 10 mg/kg divided into two doses per day. The target maintenance dose should be achieved over 2 weeks and is dependent upon patient weight, as listed in the manufacturer's product information.

Micromedex - Intranet Version
Micromedex is a comprehensive electronic drug information resource. As of June 30, 2000, it will no longer be available on the UIHC Informm mainframe system. Instead, Micromedex is available on the UIHC Intranet at http://micromedex.uihc.uiowa.edu. A link is also provided to this site from the Informm Patient Record under Applications ** Resources and Policies ** Micromedex. This site is only accessible within the university.

There are a variety of databases available with this resource:

 

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