Antimony toxicity

Background

• Antimony is a metalloid and will react as a metal and nonmetal
  • Shares many similar properties with arsenic
• Used to treat leishmaniasis and schistosomiasis
  • Most reported cases are due to complication of treatment
• Most common forms used for treatment are trivalent and pentavalent compounds
• Additional exposure occur from industrial exposures as inhalation of antimony dusts or fumes during processing
• Antimony is thought to exert its toxic effects due to inactivation of various thiol-containing proteins and enzymes

Stibine

• Most toxic form of antimony
• Colorless gas that is formed when antimony reacts with hydrogen
  • Can result when mixing drain cleaners containing sodium hydroxide in areas with antimony ore
• Can result in massive hemolysis

Toxicokinetics

• Absorption
  • Inhalation
  • Ingestion
  • Transcutaneous
  • Bioavailability is 15-50%
• Distribution
  • Predominately in highly vascular organs
  • Trivalent form seen in red blood cells
  • Pentavalent form accumulates in the liver
• Metabolism
  • Pentavalent form is converted to trivalent form in the liver
• Excretion
  • Trivalent form undergoes enterohepatic recirculation
  • Renal
    • Trivalent has a slow elimination with approximately 10% cleared within the first 24 hours
    • Pentavalent will have approximately 50-60% cleared within the first 24 hours

Clinical Features

Clinical features can range from mild local irritation to organ dysfunction

• GI
  • Anorexia
  • Nausea/vomiting
    • Leading to profound volume depletion
  • Abdominal pain
  • Diarrhea
  • Hemorrhagic gastritis
  • Pancreatitis
  • Can react with water in salvia, producing sufficient hydrochloric acid to cause GI burns
• CV
  • Decreases myocardial contraction
  • Decreased systolic pressure through decreased coronary vasomotor tone
  • Bradycardia
  • EKG changes
    • More common in pentavalent preparations
    • Prolonged QT
    • Inversion or flattening of T waves
    • Torsades de pointes
• Pulmonary
  • Local irritation
    • Laryngitis and Tracheitis
  • Antimony pneumoconiosis
    • Chronic exposure
    • Cough, wheezing, and exertional dyspnea
    • CXR showing diffuse, dense, punctate non-confluent opacities in the middle and lower lobes
• Renal
  • Proteinuria
  • Increased BUN
  • ATN
  • Renal failure
• Hepatic
  • Elevated aminotransferase
  • Hepatic necrosis
• Hematologic
  • Thrombocytopenia
  • Leukopenia
  • Severe anemia seen in HIV patients being treated for leishmaniasis
• Dermatologic
  • Antimony Spots
    • Papules and pustules around sweat glands
    • Can resemble varicella
  • Eczema
  • Lichenification
• Musculoskeletal
  • Myalgias
  • Arthralgias
• Reproductive
  • Increased risk of spontaneous abortion and premature labor
• Ocular
  • Local irritation
  • Conjunctivitis
  • Photophobia
  • Corneal burn

Differential Diagnosis

Heavy metal toxicity

• Aluminum toxicity
• Antimony toxicity
• Arsenic toxicity
• Barium toxicity
• Bismuth toxicity
• Cadmium toxicity
• Chromium toxicity
• Cobalt toxicity
• Copper toxicity
• Gold toxicity
• Iron toxicity
• Lead toxicity
• Lithium toxicity
• Manganese toxicity
• Mercury toxicity
• Nickel toxicity
• Phosphorus toxicity
• Platinum toxicity
• Selenium toxicity
• Silver toxicity
• Thallium toxicity
• Tin toxicity
• Zinc toxicity

Evaluation

• BMP
• CBC
• Urinalysis
• EKG to look for cardiac affects of antimony
• Cardiac monitor to assess for arrhythmia
• CXR
• Cases of stibine
  • Add type and cross, and coagulation factors as transfusions are likely required
• Serum level 0.8 - 3 μg/L (6.6-24.6 nmol/L)
• Urine level (24 hr) 0.5-6.2 μg/L (4.1-50.1 nmol/L)

Management

• Consult Toxicology or poison control
• Decontamination
  • Gastric lavage may be of benefit
  • Activated charcoal
    • Additionally may use multi-dose activated charcoal due to enterohepatic circulation
  • Dermal exposure
    • Irrigation with soap and water
• Supportive Care
  • Fluid resuscitation
  • Electrolyte repletion
  • Monitor I/Os
  • Antiemetics
  • Blood transfusions based on institutional criteria
• Chelation
  • Dimercaprol
    • 200-600mg/d IM shown in a case series to increase urinary excretion of antimony₁
  • Succimer
  • Dimercaptopropane-sulfonic acid (DMPS)
  • All have shown improved survival in animal models

Stibine

• Place on high flow oxygen
• Consider need for exchange transfusion to remove stibine-hemoglobin complexes

Disposition

• Will require admission to a monitored bed, likely ICU.

See also

• Toxicology (main)

References

Tarabar, A. Antimony. In: Goldfrank's Toxicologic Emergencies. 9th Ed. New York: McGraw-Hill; 2011: 1207-1213

1. 1. Lauwers LF, Roelants A, Rosseel PM, et al. Oral antimony intoxications in man. Crit Care Med. 1990;18:324-326.