Carbamazepine is an aromatic antiepileptic drug that has been approved for treatment of epilepsy and trigeminal neuralgia. In approximately five to ten percent of patients, carbamazepine treatment is associated with carbamazepine-induced hypersensitivity reactions, which are generally cutaneous in nature. It is also rarely (0.01 to 0.1 percent of patients) associated with severe reactions, including Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN).
Symptoms of carbamazepine-induced SJS/TEN generally occur within one to three weeks after beginning carbamazepine treatment, and are caused by immune-mediated keratinocyte cell death, leading to detachment of the skin. In SJS, less than 10% of the body surface is affected, and it is fatal in up to 10% of cases. In TEN, which is fatal in up to 50% of cases, greater than 30% of the body’s surface is affected. Both conditions are characterized by epidermal detachment and severe mucous membrane erosion over the affected area of the body.
Development of carbamazepine-induced SJS and TEN is associated with the HLA-B*15:02 allele, which is most commonly found in Asian populations. Due to the low frequency of this allele in other populations, the FDA recommends testing for the presence of the HLA-B*15:02 in the high risk populations prior to beginning carbamazepine therapy.