FDA Warns of Skin Reactions from Phenytoin Use in Patients with HLA Allele

-MedPageToday

11/24/2008- Using the antiepileptic drug phenytoin (Dilantin, Phenytek) to treat Asian patients with a particular human leukocyte antigen (HLA) allele could increase the risk of serious skin reactions, according to the FDA.

Preliminary data show patients with the HLA-B*1502 allele -- common in those with Han Chinese, Filipino, Malaysian, South Asian Indian, and Thai ancestry -- may have an increased risk of Stevens Johnson syndrome and toxic epidermal necrolysis, the agency said.

Fosphenytoin sodium (Cerebyx), a prodrug that is converted to phenytoin after administration, was also included in the warning.

"Healthcare providers should consider avoiding phenytoin and fosphenytoin as alternatives for carbamazepine in patients who test positive for HLA-B*1502," the FDA said.

Last year, the FDA issued a warning on an increased risk of Stevens Johnson syndrome and toxic epidermal necrolysis with carbamazepine, another antiepileptic drug, in patients of Asian ancestry with the HLA-B*1502 allele. (See: FDA Warns of HLA Allele Linked to Skin Reaction with Carbamazepine)

The new warning was based on a study published in the May 2008 issue of Epilepsia, which found that the HLA-B*1502 allele was found in four out of four patients with SHS associated with phenytoin treatment in a Thai population.

The frequency of the allele in a phenytoin-tolerant control group was much lower (18%), according to the study.

A May 2007 article in the same journal reported a single case of phenytoin-associated Stevens Johnson syndrome in a Chinese patient in Hong Kong who tested positive for HLA-B*1502.

The FDA said the risk for serious skin reaction with phenytoin appears to be greatest in the first few months of therapy -- similar to the risk with carbamazepine.

Phenytoin and fosphenytoin are used to control tonic-clonic (grand mal) and complex-partial seizures in epilepsy.

The agency said its investigation of the risks of the drugs is still underway.

If you or a loved one have suffered Stevens Johnson Syndrom, Toxic Epidermal Necrolysis, or other serious skin reaction as a result of Phenytoin or Fosphenytoin, you may be entitiled to compensation. Contact the Phenytoin and Fosphenytoin Sodium attorneys of Ennis & Ennis, P.A. today by filling out a free case evaluation form on this page or call us toll free at the number listed below.