In March of this year, the FDA announced that it would be investigating the anti-epileptic drugs phenytoin and fosphenytoin in connection with their potential to cause Stevens Johnson Syndrome (SJS) and toxic epidermal necrolysis (TEN). (fyi, Phenytoin is marketed as Dilantin, Phenytek and generics. Fosphenytoin sodium is marketed as Cerebyx and generics.)
One of the factors that may have played into the FDA investigation is a reported higher incidence of SJS in Asian patients taking these drugs, specifically Asians who test positive for the human leukocyte antigen allele HLA-B*1502.
While the FDA reports that as much as 15 percent of the population in China, Taiwan, Thailand, Malaysia, Indonesia and the Philippines may have this allele, they don’t believe there’s enough information to warrant testing for the allele in the US for patients of Asian ancestry—yet.
However, they do recommend screening for the allele in Asian patients who may be prescribed carbamazepine, another anti-epileptic drug associated with SJS, and that physicians not prescribe it unless “the benefit clearly outweighs the risk.” This is mystifying—what benefit could possibly negate the devastating effects of SJS? And, if SJS appears to be associated with a class of drugs—i.e., antiepileptics—why not screen accordingly?
According to the FDA press release on the subject issued earlier in March, 2009, “With carbamazepine, over 90 percent of serious skin reactions occur during the first few months of treatment. Patients who have taken the drug for longer than this without having a skin reaction are at low risk for developing one. Likewise, the risk for serious skin reactions with phenytoin seems to be greatest during the first few months of treatment.”
If there’s a known risk wouldn’t screening be prudent? What if you have the great misfortune to develop SJS and subsequently find out you may have been able to avoid it had you been screened in advance and not been prescribed the medicine? One wonders what the legal ramifications of this would be. My take—the benefits of screening could outweigh the risks of not screening from a legal perspective as well as from personal and institutional health perspectives.
More information on SJS signs and symptoms, and drugs is available on LawyersandSettlements.com.