Methemoglobinemia Medication

Updated: Jan 04, 2016
  • Author: Mary Denshaw-Burke, MD, FACP; Chief Editor: Emmanuel C Besa, MD  more...
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Medication

Medication Summary

Unless methemoglobinemia is severe or symptomatic, treatment is purely for cosmetic or psychological reasons. Various agents can reduce the methemoglobin levels to within the reference range (~1%) or at least to acceptable levels (5-10%).

Methylene blue is the first-line antidotal therapy. Ascorbic acid and riboflavin have been used. N -acetylcysteine reduces methemoglobin levels but is not yet approved for the treatment of methemoglobinemia. Cimetidine can be used in dapsone-induced methemoglobinemia. Hyperbaric oxygen and exchange transfusion should be considered when methylene blue treatment is ineffective or contraindicated.

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Antidotes, Other

Class Summary

Antidotes (eg, methylene blue) are used to counteract methemoglobinemia, acting as cofactors in the nicotinamide adenine dinucleotide phosphate (NADPH)-dependent methemoglobin reductase system. Cimetidine may be used in dapsone-induced methemoglobinemia.

Methylene blue

Methylene blue increases the activity of nicotinamide adenine dinucleotide (NADH)-methemoglobin reductase in red blood cells (RBCs), assisting in the conversion of ferric (Fe3+) to ferrous (Fe2+) iron. It is available as a 1% solution (10 mg/mL). Most patients require only 1 dose. Resolution of toxicity should be seen within 1 hour, often within 20 minutes.

The US Food and Drug Administration (FDA) warns against using methylene blue concurrently with serotonergic psychiatric drugs, unless such usage is indicated for life-threatening or urgent conditions. Methylene blue may increase central nervous system (CNS) serotonin levels as a result of monoamine oxidase (MAO)-A inhibition, increasing the risk of serotonin syndrome.

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Vitamins, Water Soluble

Class Summary

Vitamins are essential for normal metabolic functioning of the body. Important: they act as cofactors in erythrocyte glutathione reductase and NADH dehydrogenase.

Ascorbic acid (Vita-C, Ascocid-500, C-Gel, Chew-C)

Ascorbic acid is an antioxidant and coenzyme for reduction. It may be helpful in the treatment of congenital methemoglobinemia if used daily and on a continual basis. Although it can occasionally reduce the cyanosis associated with chronic methemoglobinemia, it has no role in the treatment of acute acquired methemoglobinemia.

Riboflavin (Ribo-100)

Riboflavin can reduce the cyanosis associated with chronic methemoglobinemia but has no role in the treatment of acute severe acquired methemoglobinemia.

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Histamine H2 Antagonists

Class Summary

Cytochrome P-450 inhibitors are recommended only for patients with methemoglobinemia secondary to dapsone.

Cimetidine (Tagamet HB 200)

Cimetidine inhibits conversion of dapsone to its oxidizing metabolite, dapsone hydroxylamine, by the P-450 system, thereby preventing further development of dapsone-induced methemoglobinemia.

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