Arsenic Poisoning

• Found in some pesticides and industrial chemicals

• Symptoms usually appear within 1 h after ingestion but may be delayed as long as 12 h

• Abdominal pain, vomiting, watery diarrhea, and skeletal muscle cramps

• Profound dehydration and shock may occur

• In chronic poisoning, symptoms can be vague but often include

  • Pancytopenia

  • Painful peripheral sensory neuropathy

  • Skin changes (eg, melanosis, keratosis, and desquamating rash)

• Cancers of the lung, bladder and skin have been reported

• Urinary arsenic levels may be falsely elevated after certain meals (eg, seafood) that contain large quantities of relatively nontoxic organic arsenic

Emergency measures

• Perform gastric lavage

• Activated charcoal is of uncertain benefit because it binds arsenic poorly

• Administer intravenous fluids to replace losses due to vomiting and diarrhea

Antidote

• For severe acute intoxication

  • 2,3-dimercaptopropanesulfonic acid (DMPS, Unithiol) is the preferred parenteral chelator

  • Dosage: 3–5 mg/kg intravenously every 4 hours

  • Although there is no FDA-approved commercial formulation of DMPS in the United States, it can be obtained from some compounding pharmacies

• An alternative parenteral chelator is dimercaprol

  • It comes as a 10% solution in peanut oil

  • Dosage: 3–5 mg/kg intramuscularly every 4–6 hours for 2 days

  • Side effects include nausea, vomiting, headache, and hypertension

• If GI symptoms allow, switch to the oral chelator succimer (dimercaptosuccinic acid, DMSA), 10 mg/kg every 8 hours, for 1 week

• Consult a medical toxicologist or regional poison control center (1-800-222-1222) for advice regarding chelation