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Oxcarbazepine Has Lower Costs, Fewer Adverse Effects Than Carbamazepine

Oct. 17, 2002
Laurie Barclay, MD
Reviewed by Gary D. Vogin, MD

Three studies presented at the 5th European Congress on Epileptology, held in Madrid, Spain, report on the benefit of oxcarbazepine (Trileptal). The first showed that compared with carbamazepine, oxcarbazepine lowered healthcare utilization and costs in a managed care setting; the second showed fewer adverse events and hospitalizations; and the third was a meta-analysis which supports the use of oxcarbazepine as monotherapy in generalized tonic-clonic seizures (GTCS).

"The results of these studies suggest that treatment with Trileptal is a good option, in terms of both tolerability and cost-effectiveness," Michael T. Halpern, MD, PhD, MPH, lead author of the first study from Exponent, Inc., says in a news release.

Using data from the U.S. Food and Drug Administration adverse event reporting system from Apr. 1, 2000, to June 30, 2000, Halpern's group identified 43 adverse events for oxcarbazepine and 307 for carbamazepine. Both groups were similar in age distribution and in proportions of patients receiving monotherapy versus polytherapy.

Rate of hospitalization for adverse events was 74.4% in the oxcarbazepine group and 76.2% in the carbamazepine group; average duration of hospitalization for reported adverse events was 4.98 days with oxcarbazepine and 5.58 days with carbamazepine; and the mean cost of hospitalization for adverse events was $4,983 for oxcarbazepine and $5,583 for carbamazepine. This 11% reduction in hospital costs with oxcarbazepine resulted a cost savings per adverse event of $600.

"In a managed care setting, oxcarbazepine may be associated with lower healthcare use and costs than carbamazepine, among patients beginning therapy," write Luke Boulanger, MA, from Boston Health Economics, Inc., coauthor of the second study.

In this retrospective cohort study using administrative claims data between Feb. 1, 2000, and Dec. 31, 2000, 453 patients were eligible for inclusion, including 414 in the carbamazepine cohort and 39 in the oxcarbazepine cohort. Over six months, serum drug-level assays increased by 10.3% and 20.5% in the oxcarbazepine and carbamazepine cohorts, respectively; liver function tests increased by 12.8% and 7.5%; and physician visits increased by 2.5% and 6.7%. Emergency department visits decreased by 15.4% and 7.3%, respectively, and hospitalizations by 7.7% and 0.2%.

"Correspondingly, mean medical costs per patient were $484 lower in the oxcarbazepine cohort, which more than offset the higher medication costs ($261) of oxcarbazepine and resulted in an overall per-patient cost saving of $222," the authors write.

Although oxcarbazepine is not approved for GTCS in the U.S., the third study may help provide some insight into what to expect for physicians who have considered using it for this indication.

"In this meta-analysis, Trileptal, given as a monotherapy, helped control seizures over the long term in patients with GTCS," says author Gunter Kramer, MD, from the Swiss Epilepsy Center in Zurich, Switzerland. "Additionally, seizure control with important because it helps avoid the issues associated with polypharmacy, such as drug-drug interactions or cumulative side effects."

Pooled data from five multicenter, double-blind, randomized, active-control, parallel-group trials, four in adults and one in children, with either untreated newly diagnosed or refractory epilepsy, included data from 266 patients who reported at least one GTCS at baseline. These patients included 149 receiving a flexible oxcarbazepine-dose as monotherapy for 11 to 14 months, and 117 active controls managed on phenytoin, valproate, carbamazepine, or phenobarbital.

During double-blind treatment, there were no major differences in GTCS frequency change from baseline, percentage of patients who were seizure-free, and completion of active treatment between oxcarrrbazepine and active control patients. The odds ratio of retention rates for oxcarbazepine compared with active controls was 0.83 (95% confidence interval, 0.51-1.35).

The most common adverse events were headache (32.9% vs. 36.8%), somnolence (26.7% vs. 15.2%), and dizziness (16.8% vs. 17.6%), in the oxcarbazepine and active control groups, respectively. "Oxcarbazepine monotherapy is effective, well tolerated, and clinically useful in GTCS," the authors write.

Novartis Pharma AG funded these studies.

5th European Congress on Epileptology: Abstracts P359, P475, P491. Oct. 6-10, 2002.

© 2002 Medscape