Epilepsy, Bipolar Drug To Recommend Genetic Test For Patients Of Asian Ancestry

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Main Category: Epilepsy
Also Included In: Bipolar;  Diabetes;  Regulatory Affairs / Drug Approvals
Article Date: 12 Dec 2007 - 13:00 PDT

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Manufacturers of carbamazepine (Carbatrol, Equetro, Tegretol), a drug used for the treatment of epilepsy, bipolar disorder, and neuropathic pain, have agreed to advise in their labeling that patients of Asian ancestry first have a genetic test before starting treatment. A number of people of Asian ancestry are susceptible to developing a serious skin reaction to the medication.

Janet Woodcock, M.D., Deputy Commissioner for Scientific and Medical Programs, Chief Medical Officer, Acting Director of the Center for Drug Evaluation and Research, FDA, said "Science is now letting us individually treat patients based on how their body might react to a drug. When being considered for treatment with carbamazepine, genetically high-risk patients can be given a test that will help their health care providers make personalized drug treatment decisions and help avoid potentially serious skin reactions."

The label already has a warning about a rare but severe skin reaction, which can sometimes be life-threatening - these can include toxic epidermal necrolysis and Stevens-Johnson syndrome, multiple skin lesions, blisters, fever, itching and other symptoms. However, the present labeling has no mention of patient ancestry.

The risk of developing the skin reaction for a patient of Asian ancestry is about ten times greater than for Caucasian patients - a Caucasian patient runs a 1 to 6 per 10,000 risk of developing the skin reaction.

For the test to be carried out, the doctor or health care professional will need to draw some of the patient's blood and send it to a laboratory. The FDA estimates that approximately 5% of patients being considered for treatment with carbamazepine are of Asian ancestry. An inherited gene variant, called HLA-B 1502 is found almost exclusively among people with Asian ancestry. This gene variant is strongly linked to serious skin reactions with this drug. The FDA stresses that a patient who tests positive for this should not take carbamazepine, unless the benefits stack up strongly in favor, compared to the skin reaction risk.

If you are a patient of Asian ancestry and you have been taking this medication for a few months, without any skin reaction, you will most likely not have this gene. If you are taking this medication and feel concerned about your risk you should not stop taking carbamazepine without first checking with your doctor.

-- Carbatrol
-- Equetro
-- Tegretol

Written by - Christian Nordqvist


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