Tragic medication error leads to death, public shaming

I just saw an article about a girl in Texas who died in March 2005 due to a similar-name medication error. Her family is running mobile billboards denouncing the pharmacy responsible. The family had been using stationary billboards for their message, but a judge’s order brought the billboard ads down.

According to the newspaper article, 2-year-old Alyssa Renee Rodriguez was treated in March 2005 for lead poisoning, and prescribed edetate calcium disodium. This drug has the brand name Calcium Disodium Versenate, and is often written “CaNa2EDTA” or just “Ca EDTA”. CaNa2EDTA is a common treatment for lead poisoning along with oral succimer, penicillamine, and British anti-Lewisite.

EDTA is “ethylenediaminetetraacetic acid” or “edetate” and is a chelating agent. Chelators bind to heavy metal ions, pulling them out of solution. Thus, EDTA compounds are used to treat acute heavy metal poisonings. CaNa2EDTA in particular is good for iron poisoning, and is listed by LexiComp as “possibly useful in poisoning by zinc, manganese, and certain heavy radioisotopes.”

Instead, the patient received edetate disodium (brand name Endrate, written as “Na2EDTA”) which is for hypercalcemia or digitalis-induced cardiac arrhythmia.

If given to a patient with a normal calcium level, Na2EDTA causes hypocalcemia. A patient with hypocalcemia will show muscle tetany, hyperreflexia, Chvostek’s sign (facial twitching if you tap CN VII over the ear), and Trousseau’s sign (carpal twitch after inflating a blood pressure cuff.)

An Aug 2006 article in Pediatrics discusses three cases of death from hypocalcemia due to edetate disodium. The first case occurred in Texas in Feb 2005, involving a 2-year-old girl. (There is a chance this is the Rodriguez case.)

The patient presented with a capillary blood lead level of 47 ug/dL. She was admitted and written a prescription for Na2EDTA, which was later corrected by a pediatrics resident to CaNa2EDTA. At 4pm, the girl received IV CaNa2EDTA as intended. However, the next morning at 4am her IV was re-hung with Na2EDTA. By 5am, her serum Ca dropped to 5.2 mg/dL (range 8.5-10.5), and at 7am her mother found her not breathing. At 8:12am she died despite full resuscitation efforts and repeated injections of calcium chloride. Labs drawn during the code showed a serum Ca less than 5.0 mg/dL. If you have access, read the article for more.

The other two cases in the Pediatrics article involve practitioners using chelating therapy for off-label uses. The second patient was a 5-year-old in Pennsylvania who received Na2EDTA to treat his autism. The third patient was a 53-year-old woman being treated for heavy metal poisoning by an ND (naturopath) in Oregon. Both of these could also be Na2EDTA vs. CaNa2EDTA errors, but it’s not clear since neither case presented in a way that most MDs would treat with any kind of chelation therapy.

The Pediatrics article has a great suggestion for avoiding this kind of error — don’t stock Na2EDTA. UpToDate notes “Chelation of ionized calcium, using sodium EDTA or intravenous phosphate, has the advantage of almost immediate onset of action. However, toxicity limits the use of these agents, and they have been superseded by the treatments described above.”

The pharmacy involved is Cardinal Health 109, which is a subsidiary of Cardinal Health, the medical supply giant headquartered in Dublin, OH. According to a Cardinal SEC filing, “109″ used to be Owen Healthcare of Houston, TX before it was acquired by Cardinal. Cardinal Health 109 contracts with hospitals to run their pharmacy services. In the article, the Rodriguez attorney claims that “Talks stalled when Cardinal Health 109 Inc. insisted the pharmacist and pharmacy technician not be sued individually.” Neither the hospital nor the physicians are a party to this case, although I imagine it is possible they settled individually.

I hope that hospitals with decision support systems put rules in place to prevent Na2EDTA from being dispensed to children without multiple MD/PharmD approvals. It’s possible that many already do. Is there a list of medications that are frequently restricted by hospital computer systems?