Usual Adult Dose for Methemoglobinemia

Drug-Induced Methemoglobinemia:
Methylene blue injection 1%:
0.1 to 0.2 mL/kg IV very slowly over a period of several minutes; may repeat in one hour if necessary

Acquired Methemoglobinemia:
Methylene blue injection 0.5% [Provayblue (TM)]:
1 mg/kg IV over 5 to 30 minutes; if the methemoglobin level remains greater than 30% or if symptoms persist, a repeat dose of 1 mg/kg IV may be given one hour after the first dose; if methemoglobinemia does not resolve after 2 doses, consider alternative interventions

Comments:

• Check individual product labeling for approved indications.
• Inject IV very slowly over a period of several minutes to prevent local high concentration of the compound from producing additional methemoglobin.
• Do not exceed recommended dosage.
• Do not administer subcutaneously or intrathecally.
• Monitor vital signs, electrocardiogram, and methemoglobin levels during therapy and through resolution of methemoglobinemia.

Usual Pediatric Dose for Methemoglobinemia

Drug-Induced Methemoglobinemia:
Methylene blue injection 1%:
0.1 to 0.2 mL/kg IV very slowly over a period of several minutes; may repeat in one hour if necessary

Acquired Methemoglobinemia:
Methylene blue injection 0.5% [Provayblue (TM)]:
1 mg/kg IV over 5 to 30 minutes; if the methemoglobin level remains greater than 30% or if symptoms persist, a repeat dose of 1 mg/kg IV may be given one hour after the first dose; if methemoglobinemia does not resolve after 2 doses, consider alternative interventions

Comments:

• The dosage of this drug should be calculated based on lean body weight.
• Therapy does not usually exceed one day.
• Check individual product labeling for approved indications.
• Inject IV very slowly over a period of several minutes to prevent local high concentration of the compound from producing additional methemoglobin.
• Do not exceed recommended dosage.
• Do not administer subcutaneously or intrathecally.
• Monitor vital signs, electrocardiogram, and methemoglobin levels during therapy and through resolution of methemoglobinemia.
• Some products may be given orally or IV. Check the manufacturer product labeling for more information. A suitable dilution for oral dosing would be 10 to 20 mL of the 0.5 % solution diluted to 100 to 200 mL with water for injection. The high volume is suggested to reduce the degree of GI disturbance and dysuria.

Renal Dose Adjustments

Approximately 40% of this drug is excreted by the kidneys. Patients with any renal impairment should be monitored for toxicities and potential drug interactions for an extended period following therapy.

Liver Dose Adjustments

Methylene blue is extensively metabolized in the liver. Monitor patients with any hepatic impairment for toxicities and potential drug interactions for an extended period following therapy.

Precautions

US BOXED WARNINGS:
WARNING: SEROTONIN SYNDROME WITH CONCOMITANT USE OF SEROTONERGIC DRUGS:

• This drug may cause serious or fatal serotonergic syndrome when used in combination with serotonergic drugs. Avoid concomitant use of this drug with selective serotonin reuptake inhibitors (SSRIs), serotonin, and norepinephrine reuptake inhibitors (SNRIs), and monoamine oxidase inhibitors.

Dialysis

Data not available

Other Comments

Administration advice:

• This drug should only be administered by healthcare professionals in facilities equipped to treat anaphylaxis.

• Do not refrigerate or freeze.
• Keep the ampoule in the original package to protect from light.

• Use product immediately after opening.

• This drug may be diluted in 50 mL glucose 50 mg/mL (5%) solution for injection to avoid local pain (especially in children).
• Precipitation has been reported when this drug has been diluted with sodium chloride 0.9%, saline (due to presence of chloride ions which have been shown to reduce the solubility of methylene blue).
• This drug is incompatible with caustic alkalis, iodides and dichromates, and oxidizing and reducing substances.