Sodium thiosulfate fails to reduce nitrite-induced methemoglobinemia in vitro.
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.
Matteucci
Michael John
MJ
Emergency Medicine Department, Naval Medical Center, San Diego, CA, USA. dr_soar@hotmail.com
Reed
William Job
WJ
Tanen
David Alan
DA
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*
D000975:Antioxidants; D013885:Thiosulfates; C017717:sodium thiosulfate; D012977:Sodium Nitrite