 |
 |
 |
|
 |
FDA Home Page | Search FDA Site | FDA A-Z Index | Contact FDA
Consumer Update |
Manufacturers of drugs containing carbamazepine--a drug used to treat epilepsy, bipolar disorder, and neuropathic pain--have agreed to recommend on the labeling that patients with Asian ancestry get a genetic blood test before starting therapy with the products. The blood test can identify a significantly increased risk of developing a rare, but serious, skin reaction.
Carbamazepine is sold under the brand names Carbatrol, Equetro and Tegretol.
Why the New Labeling?
Although the risk of skin reactions is estimated to be about 1 to 6 per 10,000 new users of the drug in countries with mainly white populations, the risk is estimated to be about 10 times higher in some Asian countries.
Studies have found a strong association between certain serious skin reactions and an inherited variant of HLA-B* 1502, an immune system gene found almost exclusively in people with Asian ancestry. Patients testing positive for this gene should not be treated with carbamazepine unless the benefit clearly outweighs the increased risk of these serious skin reactions.
Warnings About Skin Reactions
In its Dec. 12, 2007, announcement addressing the new labeling, FDA explained that the prescribing information for these drugs already includes a warning that rare but severe--and sometimes life-threatening--skin reactions can occur for all patients starting carbamazepine therapy. The life-threatening skin reactions include toxic epidermal necrolysis and Stevens-Johnson syndrome, characterized by multiple skin lesions, blisters, fever, itching and other symptoms.
The skin reaction warnings will be moved to the current boxed warning section of the labeling. The new recommendation regarding patients with Asian ancestry will also be added to the boxed warning section.
Patients who have taken carbamazepine for more than a few months and not experienced any skin reactions are unlikely to ever experience these reactions, regardless of ancestry or genetic test results. Patients currently taking carbamazepine who are concerned about these skin reactions should not stop taking the drug without first consulting their health care provider.
For More Information
FDA Press Release
http://www.fda.gov/bbs/topics/NEWS/2007/NEW01755.html
Information on Carbamazepine-FDA Alert (Dec. 12, 2007)
http://www.fda.gov/cder/drug/infopage/carbamazepine/default.htm
Information for Healthcare Professionals: Carbamazepine
http://www.fda.gov/cder/drug/InfoSheets/HCP/carbamazepineHCP.htm
Date Posted: December 17, 2007
