0071643192.pdf

TOXICOLOGY

A 2-year-old girl is brought in to the ED by her parents following sus-

pected ingestion of rat poison containing difenacoum 1 hour earlier. She

has no past medical history, is acting normally, and the physical exami-

nation is unremarkable. What workup and intervention should be con-

sidered at this time?

Nothing at this time. It is very unlikely that the labs will be abnormal and

very rare to have clinically significant bleeding after a one-time unintentional

ingestion. A conservative approach is to have follow-up coagulation studies done

daily for 2–3 days.

Superwarfarins

Most home rodenticide products contain a superwarfarin such as brodifa-

coum. Symptoms occur 1–2 days following ingestion.

MECHANISM/TOXICITY

■ Superwarfarins act similarly to warfarin by inhibiting production of vita-

min K dependent clotting factors (II, VII, IX, X); however, the duration of

anticoagulation may extend for weeks.

SYMPTOMS/EXAM

■ Symptoms are due to bleeding (brain, GI, vaginal, etc.).

■ Onset of symptoms is 1–2 days following ingestion.

DIAGNOSIS

■ PT/INR measurement can determine the extent of anticoagualation from

superwarfarins.

TREATMENT

■ Vitamin K supplementation for elevated INR. Large ingestions may

require high doses for prolonged periods of time.

■ Prophylactic vitamin K (prior to elevation of INR) is notindicated (dura-

tion of action of superwarfarin is much longer than that of vitamin K).

■ Acute bleeding requires FFP or cryoprecipitate to reverse anticoagulation.

Strychnine

A rodenticide with significant human toxicity, its use in home products has

largely been supplanted by the superwarfarins.

MECHANISM/TOXICITY

■ Inhibits glycine receptors within the spinal cord →uncontrolled muscular

contraction

SYMPTOMS/EXAM

■ Strychnine poisoning produces rapid onset involuntary muscle contrac-

tions, opsithotonus, hyperreflexia, clonus, and trismus. Mental status is not

affected.

Duration of anticoagulation

following superwarfarin

ingestion may extend for

weeks.

Generalized, uncontrolled

muscular activity with normal

mental status is suggestive of

strychnine poisoning.