Americans of Ethnic Origin May be at Higher Risk for SJS

Washington, DCThey may originally hail from other countries, but many Americans of diverse ethnic origin may have a concern with SJS and Stevens Johnson Syndrome (SJS) given their particular ethnic make-up and their relationship to the human leukocyte antigen allele HLA-B*1502. According to a recent alert issued by the US Food and Drug Administration (FDA), Americans of Asian decent who ingest certain drugs could experience adverse SJS reactions that include toxic epidermal necrolysis (TEN).

The drugs in question are phenytoin and fosphenytoin and are marketed under various names. Phenytoin is marketed as Dilantin and Phenytek, together with generics. Fosphenytoin sodium is marketed as Cerebyx, as well as in generic form.

A previous revelation established that carbamazepine, an anti-epileptic drug, increases the risk of SJS and TEN in Asian patients with the HLA-B*1502 allele. The FDA previously recommended the screening of these patients prior to the administering of carbamazepine.

According to information posted online by the FDA, 15 percent or greater of the population in parts of China, Taiwan, Thailand, Malaysia, Indonesia and the Philippines may carry the HLA-B*1502 allele, making them more susceptible for acquiring SJS and TEN symptoms. The frequency in South Asia (including India) is somewhat lower, according to the FDA. For Japan and Korea, the incidence rate is under one percent.

What makes this of interest to the US are the numbers of immigrants—both legal and illegal—who now call the US home after coming here from other parts of the world. Major cities usually attract more immigrants than more rural areas of the country, much like Toronto has become a cultural melting pot in Canada.

SJS and its cousin TEN are skin conditions that can be brought on by certain types of medication. The symptoms can include serious skin lesions that are burn-like. In serious cases skin can slough away in sheets. Eyes can also be adversely affected and SJS / TEN patients can experience blisters and lesions in the mouth.

Many of the more serious SJS patients are treated in the burn units of hospitals. The condition can affect both adults and children alike. Some have died from SJS.

With carbamazepine, over 90 percent of serious skin reactions occur during the first few months of treatment, according to the FDA. Asian patients who have taken the drug for longer periods without having a skin reaction are at low risk for developing one. Likewise, the risk for serious skin reactions with phenytoin appears to be greatest during the first few months of treatment.

The potential risk inherent with phenytoin and fosphenytoin is still under review and there is insufficient information at this point to recommend testing for the allele before commencing therapy.

However, FDA is recommending that physicians avoid using phenytoin as a substitute for carbamazepine in patients who test positive for the HLA-B*1502 allele.

Patients on phenytoin, fosphenytoin or carbamazepine who develop a skin rash should contact their physicians immediately.