|SOFT - TIAFT 1998||Poster Session 3||Thursday October 8, 1998|
CASE REPORT: DEATH OF AN INFANT INVOLVING BENZOCAINE|
Ann Marie Gordon and Barry K. Logan
Washington State Toxicology Laboratory, Seattle, WA, USA
|A case is presented of a four month old Hispanic male found unresponsive in bed. Efforts to resuscitate were unsuccessful. The toxicological evaluation revealed benzocaine at a concentration of 3.48 mg/L and methemaglobin of 36% (normal 0.4 - 1.5). The coroner investigated the source of the benzocaine and discovered that the child was being treated with "Zenith Goldline Allergen Ear Drops" 1.4% w/v benzocaine and 5.4% w/v antipyrine. There was an admission that on the day prior to the child's death, he was treated with 3X the prescribed dose by a caregiver.
Benzocaine is available in many over the counter as well as prescription drugs. It's potential for inducing methemaglobinemia has long been recognized. Methema-globinemia occurs when more than 1% of the heme iron is oxidized to the ferric form. The oxidized hemoglobin (methemoglobin) is incapable of reversibly binding oxygen. Infants less than 6 months are at increased risk for methemaglobinemia due to lower levels of enzyme systems needed to reduce ferrihemoglobin to ferrohemoglobin.
There are no reported blood benzocaine blood concentrations in the literature for the cases where death or illness from benzocaine has been reported. We also determined the blood benzocaine concentrations in 4 other cases and found levels from 0.46 - 1.49 mg/L. Three of the four were polydrug users from the same Washington State county where benzocaine was purportedly used to "cut" cocaine. Methemglobin in these cases ranged from 36 - 69%. However, elevated methemoglobin can occur as an artifact in post mortem blood.