WASHINGTON The Food and Drug Administration has announced that manufacturers of drugs containing the active ingredient carbamazepine have agreed to add the recommendation that before starting therapy with the drugs, patients with Asian ancestry should get a blood test that can identify a significantly increased risk of developing a rare, but serious, skin reaction, to its drugs’ labels.
Carbamazepine is a drug used for the treatment of epilepsy, bipolar disorder and neuropathic pain. It is sold under the brand names Carbatrol, Equetro and Tegretol.
The prescribing information for these drugs already includes a warning that for all patients starting carbamazepine therapy, regardless of ethnicity, rare but severe and sometimes life-threatening skin reactions can occur. These life-threatening skin reactions include toxic epidermal necrolysis and Stevens-Johnson syndrome, characterized by multiple skin lesions, blisters, fever, itching and other symptoms.
The risk of these reactions is estimated to be about 1 to 6 per 10,000 new users of the drug in countries with mainly white populations. However, the risk is estimated to be about 10 times higher in some Asian countries.
The skin reaction warnings will be moved to the current boxed warning section of the labeling. The new recommendation that health care providers give patients with Asian ancestry a genetic test before starting treatment will also be added to the boxed warning section.
Carbatrol is manufactured by Shire Pharmaceuticals; Equetro is manufactured by Validus Pharmaceuticals; and Tegretol is manufactured by Novartis.