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

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

  • 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.
  • Consult Toxicology or poison control

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.