Pharmacogenetics Newsletter

Volume 2, Issue 7, 02/16/2010

Question

Why should patients of Asian descent receive human leukocyte antigen (HLA)-B genetic testing before being prescribed carbamazepine (Carbatrol; Equetro; Tegretol)?

Answer

The use of carbamazepine (Carbatrol; Equetro; Tegretol) is common for the treatment of acute manic and mixed episodes associated with bipolar I disorder, epilepsy, and trigeminal neuralgia.(1,2)  Unfortunately, carbamazepine is associated with a number of problems and/or side effects one of which includes hypersensitivity reactions that most commonly involves the skin, but is also associated with other organs (liver, kidneys) as well.(3)  Many patients will typically exhibit a triad of fever, rash, and lymphadenopathy, but are also known to have eosinophilia and atypical lymphocytosis.(3,4)  As it relates to the hypersensitivity reaction involving the skin, the condition can range from a mild skin rash (generalized exanthematous eruptions) to the development of life-threatening skin reactions that include Stevens-Johnson syndrome (SJS) and/or toxic epidermal necrolysis (TEN).(3-6)  While the incidence in the general population is low, the development of SJS and TEN can lead to an increase in morbidity and mortality.(5-7) 

Are there any risk factors that predispose patients to carbamazepine induced SJS and/or TEN?
Yes.  It appears that patients of ...

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