Patients with Asian ancestry are being advised to take a genetic blood test before starting to use medicines containing the active ingredient carbamazepine.
The FDA has announced that the manufacturers of drugs containing the ingredient have agreed to alter the labels on the medicines.
The test has been designed to identify whether such patients are at a significantly increased risk of developing rare but serious skin reactions.
These include toxic epidermal necrolysis and Stevens-Johnson syndrome, which is characterised by multiple skin lesions, blisters, fever and itching.
The risk of these reactions is estimated to be about one to six per 10,000 new users of the drug in countries with mainly Caucasian populations.
However, the risk is estimated to be about 10 times higher in some Asian countries.
Janet Woodcock, the FDA’s deputy commissioner for scientific and medical programmes, said: “When being considered for treatment with carbamazepine, genetically high-risk patients can be given a test that will help their healthcare providers make personalised drug treatment decisions and help avoid potentially serious skin reactions.”
Carbamazepine is used to treat epilepsy, bipolar disorder and neuropathic pain, and is sold under the brand names Carbatrol, Equetro and Tegretol, although generic versions of the drug are also available.
Carbatrol is manufactured by Shire, Equetro by Validus and Tegretol iby Novartis.
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