Which of the following should be administered to this patient?

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This patient has methemoglobinemia, a medical emergency. Any medication (eg, topical anesthetic) suspected to be the cause of the methemoglobinemia requires immediate discontinuation. The antidote for acquired symptomatic methemoglobinemia or high levels of methemoglobin (as measured by co-oximetry) is methylene blue. Methylene blue acts as an electron acceptor for NADPH and is reduced to leucomethylene blue, which in turn reduces methemoglobin to hemoglobin. High-dose ascorbic acid (vitamin C) acts as a reducing agent and can be used when methylene blue is unavailable or contraindicated (eg, glucose-6-phosphate dehydrogenase deficiency). (Choice A) Dimercaprol, a chelating agent, is most commonly used in the treatment of lead poisoning to increase the urinary and fecal excretion of lead. (Choice B) Fomepizole is used for the treatment of ethylene glycol or methanol ingestion. Through the inhibition of alcohol dehydrogenase, fomepizole prevents the metabolism of these alcohols to their toxic metabolites. (Choice C) Glucagon can be used after the ingestion of a beta blocker or calcium channel blocker by activating adenylate cyclase, which increases intracellular calcium and improves cardiac contractility. (Choice E) N-acetylcysteine is the antidote for acetaminophen poisoning. It acts by restoring glutathione, which metabolizes acetaminophen's toxic metabolite, N-acetyl-p-benzoquinone imine (NAPQI), to nontoxic metabolites. (Choice F) Pralidoxime is an antidote for cholinergic toxicity (eg, acetylcholinesterase inhibitors such as organophosphates). Pralidoxime is given with atropine and reactivates the cholinesterase enzyme. Educational objective: Patients with acquired symptomatic methemoglobinemia or high levels of methemoglobin can be treated with methylene blue or high-dose ascorbic acid. References: A 12-day-old boy with methemoglobinemia after circumcision with local anesthesia (Lidocaine/Prilocaine). (http://www.ncbi.nlm.nih.gov/pubmed/27747692) Lidocaine-induced methemoglobinemia: a clinical reminder. (http://www.ncbi.nlm.nih.gov/pubmed/25637615)

Which of the Following Should Be Administered to This Patient