sulfa and nitrate drugs

[faisal 2000]

hi there
as i know nitrate drugs (nitroglycerin) and sulfa drugs(sulfamethazole) can cause methemoglobinemia
could any one explain the mechanism
and if the patient take any of these drugs
which cells can be damaged?

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[SBR249]

Not 100% positive but I think sulfa drugs can generate reactive oxygen species that deplete antioxidants. The depletion of antioxidants then allows accumulation of methemoglobin (remember that methemoglobin is generated naturally in the body and kept in check by anti-oxidative mechanisms which can be saturated).

It's the same reason sulfa drugs cause hemolysis in G6PD deficient patients. G6PD is part of the pentose phosphate pathway that generates NADPH necessary for the regeneration of glutathione, an antioxidant.