Methylthioninium chloride (Methylene blue) intravenous for adults

Who can administer

May be administered by registered competent doctor or nurse/midwife

This monograph only refers to the INTRAVENOUS use of this product
Advise contact with the National Poisons Information Centre (NPIC) before using this drug
Unlicensed preparation
Flush line before and after with Glucose 5%
Intravenous methylthioninium chloride should be avoided in patients who have been treated recently with serotonergic antidepressants, e.g.SSRIs, SNRIs, MAOIs, venlafaxine, and opioids (fatal serotonergic symdrome reported)
- If combination cannot be avoided, monitor for the emergence of serotonin syndrome and if symptoms occur, discontinue use of methylthioninium and initiate supportive treatment

Proveblue Methylthioninium chloride (methylene blue) injection 5mg per mL

Available as 10mg in 2mL and 50mg in 10mL ampoules (50mg in 10mL usually in stock)

Already in solution

Draw up using a 5 micron filter needle

Glucose 5% ONLY

Slow intravenous injection

Dilute in 50 to 100mL Glucose 5%
Administer very slowly over 5 minutes to prevent high local concentrations of the compound from producing additional methaemoglobin

Methaemoglobinaemia

After discussion with NPIC, give 1 to 2mg/kg initially
Give further doses as advised by NPIC (which are normally given after 30 to 60 minutes)

Renal impairment

Should be used with caution in patients with moderate to severe renal disease since there is limited data available. Lower doses may be needed. Contact NPIC

Monitor MetHb concentrations every 30 to 60 minutes to assess effectiveness, or sooner if cyanosis recurs
- Note that methaemoglobinaemia may recur and further treatment may be required
Monitor all patients until at least 6 hours after treatment

Monitor ECG, blood pressure, oxygen saturations
Monitor for serotonin syndrome if administered to patients who are on serotonergic drugs

Also consulted: Toxbase printed 02/07/2025

Antidotes and chelators