Methylene blue
Administration
- Type: Antidote
- Dosage Forms:
- Routes of Administration: IV
- Common Trade Names:
Adult Dosing
- Acquired methemoglobinemia: 1 mg/kg IV over 5-30min, may repeat in 1h with up to 1 mg/kg IV if methemoglobin level still >30% or symptoms persist
- Drug-induced methemoglobinemia: 1-2 mg/kg IV slowly over several minutes
Pediatric Dosing
- Same as weight-based adult dosing
Special Populations
- Pregnancy Rating: Fetal risk has been demonstrated
- Lactation risk: Infant risk cannot be ruled out
- Renal dosing: no adjustment
- Hepatic dosing: no adjustment
Contraindications
- Allergy to class/drug
- G6PD deficiency
Adverse Reactions
Serious
- Hemolytic anemia
- Syncope
- Serotonin syndrome
Common
- Skin discoloration, urine discoloration, hyperhidrosis
- Nausea, abnormal taste
- Limb pain
- Dizziness, headache
Pharmacology
- Half-life: 24h
- Metabolism: Hepatic
- Excretion: Mostly renal
Mechanism of Action
- Promotes non-enzymatic redox conversion of methemoglobin to hemoglobin