Antidote for sodium nitrate poisoning is :

A i.e. Methylene blue- In Methemoglobinemia, iron within hemoglobin is oxidized from the ferrous (Fe++) to ferric (Fe+++) form, resulting in the inability to transpo oxygen and carbon dioxide.- It may result from exposure to oxidizing agents such as nitrites, nitratesQ, aniline dyes, and medication including local anesthetics benzocaine, lido caine, prilocaine, phenazopyridine hydrochloride, sulfonamidesQ, chloroquin, inhalant in cyanide antidote kit, nitrogen oxide, nitro & nitroso - hydrocarbons, primaquine - type antimalarialsQ, etc.- Methemoglobinemia >15% causes symptoms of cerebral ischemia, and levels >60% are usually fatal.- Congenital methemoglobinema arises from HbMI wata (a 87 II' -> Tyr) mutationQ in globin or from mutation that impair enzyme that reduce methhemoglobin to hemoglobin (eg. methemoglobin reductase, NADP diaphorase)Q.IV methylene blueQ (1mg/kg) is effective emergency therapy for >30% methemoglobinemia, symptomatic hypoxia or ischemia (but contraindicated in G6PD deficiency). Milder cases & follow up of severe cases are treated by oral methylene blue or ascorbic acidQ (300 - 600 mg/day). Severe & refractory cases require exchange transfusion & hyperbaric oxygenQ.