NEW YORK (GenomeWeb News) – Taiwan’s Department of Health said this week that it has updated the label for the anticonvulsant drug carbamazapine to warn patients of a genetic link to potentially serious side effects, and said that it plans to test patients for adverse reactions to the drug.
According to Taiwan’s National Reporting System of Adverse Drug Reactions, carbamazepine — a mood-stabilizing drug used for epilepsy and bipolar disorder — is responsible for severe adverse drug reactions such as Stevens-Johnson syndrome and Toxic Epidermal Necrolysis, also called SJS/TEN. There is a high incidence of carbamazapine-induced SJS/TEN in Taiwan compared to other countries, the DOH said.
A series of retrospective studies has shown that the human leukocyte antigen HLA-B*1502 marker — which is present in about 5 percent of the Taiwanese population — “has a very strong association” with these serious ADRs, the DOH said, prompting the label change for carbamazapine.
The updated label notes this risk and warns that “a patient who carries the HLA-B*1502 gene will have at least 193 times higher risk of developing ADR than a patient who is not a HLA-B*1502 carrier. Approximately 5% of the Taiwan population carry the HLA-B*1502 gene."
This data connecting the drug to the biomarker was drawn from retrospective studies conducted by Yuan-Tsong Chen, director of the Institute of Biomedical Sciences in Taiwan and a professor of Pediatrics and Genetics at Duke University Medical Center.
The DOH said in a statement that due to the retrospective study design, “the clinical application of the results is somewhat limited,” so it is planning to conduct a series of preventive prospective studies between 2008 and 2012 “to assess the clinical applications of the risk genes” and to determine if genetic screening “can effectively reduce the incidence of ADR.”
Chen told GenomeWeb Daily News in an e-mail that he has been invited to present the data from the biomarker studies to the US Food and Drug Administration.