N-acetylcysteine reduces methemoglobin in vitro.
OBJECTIVE
To determine whether N-acetylcysteine (NAC reduces methemoglobin.


METHODS
We carried out an in vitro laboratory experiment in which five healthy adult volunteers donated blood. Each sample was divided equally among three test tubes. Tube 1 served as a negative control. Sodium nitrite .18 mol/L with dextrose .23 mol/L was added to tube 2 and to tube 3. Next, phosphate-buffered saline solution (PBS) was added to tube 2 and NAC (200 mg/mL) to tube 3. Serial methemoglobin levels were measured over 5.5 hours.


RESULTS
Maximum methemoglobin levels were observed at 1.5 hours for both the NAC-nitrite and the PBS-nitrite sample (62.7% +/- 8.1% and 65.1% +/- 7.0%, respectively; data expressed as mean +/- SD). The mean difference in methemoglobin between NAC-nitrite and PBS-nitrite was significant at 4.5 hours (29.3% +/- 23.0%, P = .046). The mean rate of methemoglobin decline in NAC-nitrite samples was also different from that of PBS-nitrite samples (10.7% +/- 1.0% versus 2.9% +/- 2.3%, P = .002). The rate of decline was linea (zero order) in the NAC nitrite samples and represented by the equation: % change methemoglobin = .18 x time in minutes. Area under the concentration-time curve was also different among groups (P < .05).


CONCLUSIONS
In this in vitro model, NAC reduced chemically induced methemoglobin.
Division of General Pediatrics, Children's Hospital, Boston, Massachusetts, USA. wright_r@a1.tch.harvard.edu
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Wright
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Magnani
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Shannon
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Woolf
D000111:Acetylcysteine / Q000494:pharmacology*; D000328:Adult; D016166:Free Radical Scavengers / Q000494:pharmacology*; D006454:Hemoglobins / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D008706:Methemoglobin / Q000187:drug effects* / Q000378:metabolism; D010084:Oxidation-Reduction; D012977:Sodium Nitrite / Q000633:toxicity
D016166:Free Radical Scavengers; D006454:Hemoglobins; D008706:Methemoglobin; D012977:Sodium Nitrite; D000111:Acetylcysteine