Methylene Blue
Liverpool Hospital Emergency Department
Indications:
Use as an antidote for methaemoglobulinaemia
- Levels of MetHb >20% even if asymptomatic
- Evidence of tissue hypoxia
- Use as a vasopressor agent in severe vasoplegic shock
Formulation:
- 1% methylene blue 50mg/5ml
Dosage and Administration
- 1-2mg/kg as a slow IV push over 5 minutes followed by saline flush further dosing may be guided by a toxicologist.
- Generally, a single dose is required except if there is ongoing oxidising and production of MetHb.
- Measure MetHb hourly post administration on blood gases
Side Effects:
- Dysuria
- Green blue urine
Pit Falls:
Failure of treatment can occur
- Inadequate dosage
- Ongoing methhb production
- Sulfhaemoglobin
- G6PD deficiency
- Abnormal Hb
- Excessive methylene blue can cause methb (>7mg/kg)