Preventing Fatal Overdoses with anti-epileptic drug Cerebyx (fosphenytoin)

The Institute for Safe Medication Practices (ISMP) and FDA are warning healthcare professionals that potentially fatal dosing errors continue to occur with the anti-epileptic drug Cerebyx (fosphenytoin), despite clarifications in the drug's labeling that date back to 1999. FDA's MedWatch program has reports of seven cases where young children received an overdose of Cerebyx and died.

Cerebyx doses are expressed as phenytoin equivalents (PE). The problem is that electronic and printed displays in many facilities list the drug as "50 mg PE/mL, 10 mL." That could cause users to believe that a 10 mL vial contains just 50 mg PE rather than 500 mg PE, which could lead to a significant overdose.

To help prevent these errors, the ISMP article recommends that medication screen displays, facility-generated auxiliary labeling, displays on automatic dispensing cabinets and printed requisitions read "100 mg PE per 2 mL" or "500 mg PE per 10 mL." Because the 10 mL vial appears to be most frequently involved in massive overdosing, ISMP recommends that pediatric facilities consider stocking only the 2 mL vials.

ISMP notes that it would take ten of these vials to prepare a potentially fatal 1,000 mg dose. Retrieving this many vials might alert the practitioner that a dosing error has been made.

Additional Information:

ISMP Medication Safety Alert! FDA Advise-ERR: Medication Errors Associated with Cerebyx. April 10, 2008. Volume 13, Issue 7, Page 1-2.
http://www.ismp.org/Newsletters/acutecare/articles/20080410.asp