title: Sodium thiosulfate fails to reduce nitrite-induced methemoglobinemia in vitro.
abstract: OBJECTIVE
  To determine whether sodium thiosulfate (STS) produces a clinically significant decline in sodium nitrite-induced methemoglobinemia in an in-vitro model.
  
  
  METHODS
  This was an in-vitro, controlled study where methemoglobinemia was induced by the addition of sodium nitrite (0.4 mg/mL) to 35-mL aliquots of blood obtained from ten healthy volunteers. Methemoglobin (MetHb) concentrations were measured at 5-minute intervals for 30 minutes by co-oximetry, and each aliquot was then subdivided into six 5-mL samples (time zero). Sample 1 served as control. The remaining samples received serial dilutions of STS (0.125 mg, 1.25 mg, 12.5 mg, 125 mg, 1,250 mg). MetHb concentrations were measured by co-oximetry at baseline, 0, 15, 30, 45, and 60 minutes. Areas under the MetHb concentration-time curve (AUC) between time zero and 60 minutes were compared using the Kruskal-Wallis test.
  
  
  RESULTS
  Methemoglobin concentrations increased from 0.07 g/dL (+/-0.06) at baseline to 8.42 g/dL (+/-0.69) at time 0 (the addition of STS). No significant difference was detected between baseline and time 0 hemoglobin concentrations (15.8 +/- 0.5 vs. 16.1 +/- 0.6 g/dL). There was no detectable difference found between the AUCs (measured in g min/dL) of any of the STS serial dilutions or control groups (0.125 mg STS = 576.01 +/- 42.53; 1.25 mg STS = 573.47 +/- 40.82; 12.5 mg STS = 583.68 +/- 42.29; 125 mg STS = 554.75 +/- 42.68; 1,250 mg STS = 566.95 +/- 38.08; p = 0.81).
  
  
  CONCLUSIONS
  Sodium thiosulfate was not found to be an effective reducing agent for the acute treatment of methemoglobinemia.
authors.affiliation: Emergency Medicine Department, Naval Medical Center, San Diego, CA, USA. dr_soar@hotmail.com
authors.forename: Michael John
authors.initials: MJ
authors.lastname: Matteucci
authors.forename: William Job
authors.initials: WJ
authors.lastname: Reed
authors.forename: David Alan
authors.initials: DA
authors.lastname: Tanen
mesh_terms: D000975:Antioxidants / Q000008:administration & dosage / Q000627:therapeutic use*; D019540:Area Under Curve; D006801:Humans; D066298:In Vitro Techniques; D008708:Methemoglobinemia / Q000097:blood / Q000139:chemically induced / Q000188:drug therapy*; D011446:Prospective Studies; D012977:Sodium Nitrite; D013885:Thiosulfates / Q000008:administration & dosage / Q000627:therapeutic use*
chemical_list: D000975:Antioxidants; D013885:Thiosulfates; C017717:sodium thiosulfate; D012977:Sodium Nitrite