From The Carlat Psychiatry Blog, ,

Does the limited research support that oxcarbazepine is a safer and more effective treatment for bipolar disorder than its FDA-approved cousin, carbamazepine? Here is an overview of the pros and cons from a previous article in The Carlat Psychiatry Report.

Pros:

Similar effectiveness as other mood stabilizers. In mania and mixed states, hypomania, or the maintenance phase, oxcarbazepine worked as well as lithium, valproic acid, carbamazepine, and haloperidol (Vasudev A et al, Cochrane Database Syst Rev 2011;12:CD004857). 

Better at augmenting lithium. In mania, oxcarbazepine outperformed carbamazepine at increasing the efficacy of lithium.

Reduction of specific symptoms. For example, oxcarbazepine reduced impulsivity and aggression in small, placebo-controlled studies of patients with and without bipolar disorder (Mattes JA, J Clin Psychopharmacol 2005;25(6):575–579).

Less likely to cause side effects. Studies have shown that in both epilepsy and bipolar disorder, oxcarbazepine is 20% less likely to produce side effects when compared to carbamazepine.

No aplastic anemia or agranulocytosis. These conditions are not seen with oxcarbazepine, but they’re both observed at a rate of 1 in 100,000 with carbamazepine. 

Less potent inducer of CYP3A4. Being a potent inducer of CYP3A4, carbamazepine can render many medications, such as antipsychotics and antidepressants, ineffective. Whereas, oxcarbazepine induces CYP3A4 to an extent 50% less than that of carbamazepine. However, this no reassurance when it comes to the CYP3A4 interaction with oral contraceptives.

Common Ground:

Similar side effects. Both medications can cause headaches, dizziness, somnolence, or nausea. Additionally, they both carry a risk of rash, Stevenson-Johnson syndrome, and elevated liver enzymes.

Emergence of transient side effects. Side effects are most likely to occur in the first 4 weeks of treatment with both medications.

Cons:

Problematic studies. Many studies have been flawed for numerous reasons: small sample sizes, testing the effects of oxcarbazepine as an add-on to lithium, subject recruitment over too many research sites, lack of a placebo control, or a high percentage of subject dropping outs leading to results lacking statistical significance (Vieta E et al, Int J Neuropsychopharmacol 2008;11(4):445–452; (Wagner KD et al, Am J Psychiatry 2006;163(7):1179–1186).

Higher risk of hyponatremia. The risk of severe hyponatremia is 1.3% for oxcarbazepine vs 0.1% for carbamazepine; for mild it’s 30% vs 15%, respectively. Severe hyponatremia can lead to seizures, coma, and death.

Click here for more information on oxcarbazepine.