Anti-seizure drugs carry new black box warning

Two drugs used to control types of seizures now carry the Food and Drug Administration’s strongest warning for severe hypotension and cardiac arrhythmias. The drugs also carry a new warning for  serious skin disorders including the potentially fatal Stevens Johnson Syndrome (SJS) and the more severe form of the disease, toxic epidermal necrolysis (TEN).

Cerebyx (fosphenytoin sodium) Injection and Dilantin (phenytoin) are anticonvulsant drugs that work in the brain to block or slow down the spread of seizure activity. The cardiovascular risk with these drugs is associated with rapid infusion.

The rate of intravenous administration of Cerebyx should not exceed 150 mg phenytoin sodium equivalents (PE) per minute, and the rate of intravenous administration of Dilantin should not exceed 50 mg per minute in adults and 1-3 mg/kg/min (or 50 mg per minute, whichever is slower) in pediatric patients, or there becomes a cardiovascular risk.

Although the risk of cardiovascular toxicity increases with infusion rates, these events have also been reported at or below the recommended infusion rate. Reduction in rate of administration or discontinuation of dosing may be needed to reduce a patient’s risk.

Both medicines also carry a new warning for serious dermatologic reactions, skin reactions that include rashes that can be serious. There is a risk for SJS and TEN, serious allergic reactions that start with a rash that blisters over and then causes the skin to peel off in sheets. The condition can be life threatening. The SJS and TEN warning is even stronger for patients of Chinese ancestry who are taking either Cerebyrx or Dilantin.

Source: FDA