How is Methylene Blue administered?

[Stargazer100]

I was wondering how Methylene blue is administered. From what I could gather online it is typically given through an IV.
Important to mention is that it can't be dosed too fast, otherwise it will worsen the very problem it was meant to resolve. From what I read a typical dosage is 1mg/kg of Methylene blue (sometimes 2mg/kg) administered over a period of 5 to 7 minutes or slower, followed by a period of 1 hour before the next dose if a next dose is necessary.

Is the medication (very slowly) inserted at the port closest to the patient or is it inserted in the iv fluid bag? And can medication be inserted in a fluid bag of an already running IV or is the IV temporarily stopped to mix the medicate with the fluid in the bag?

Are there any other methods of administering Methylene Blue to a patient who took SN?

Is it safe to give at least one dosage of Methelyne Blue without checking blood values, thus not knowing if it's necessary? (I found resources suggesting it's not uncommon to give this medication before being certain of SN overdose so I assume the answer is that it's safe)

 

[UterEntonaur]

MB is given (via IV) at a regular and higher dose first, and then 2mg per KG of body weight, until all the methemoglobin is converted to hemoglobin (usually 24hrs tops but you see results within 0-3hrs)

The saline in the IV bag is just the transport mechanism, so usually the first dose is injected directly into the tube (that enters you), and the following doses mixed with the saline (so the "rate" can be controlled)

 

[Stargazer100]

MB is given (via IV) at a regular and higher dose first, and then 2mg per KG of body weight, until all the methemoglobin is converted to hemoglobin (usually 24hrs tops but you see results within 0-3hrs)

The saline in the IV bag is just the transport mechanism, so usually the first dose is injected directly into the tube (that enters you), and the following doses mixed with the saline (so the "rate" can be controlled)

So the initial dose is more than 2 mg? And the first dose does not need to be administered at a slow rate?

 

[UterEntonaur]

AFAIK (from the medical publications relating to SN poisoning) the first dose is always more than 2mg - but the actual amount is at the discretion of the clinician/physician - depending on the level of methemoglobin

It's very similar to the way a regime of antibiotics are taken.... your "first day dose" is always double what the regular dose should be, so it can enter your system quickly and start working, after that the slower dose just keeps the initial dose "topped up".

 

[Stargazer100]

Is methylene blue actute toxic or otherwise significantly harmful when you give up to 4 mg immediately to a person who didn't take SN? Would it be safe to give to someone based on a suspicion that he or she took SN?

 

[UterEntonaur]

Is methylene blue actute toxic or otherwise significantly harmful when you give up to 4 mg immediately to a person who didn't take SN?

So from what I understand of how SN/MB works...

Methemoglobin occurs in the red blood cells, when there's ferric iron instead of ferrous iron, which causes the lack of oxygen to the tissue. So if someone displayed a high methemoglobin level (either visually due to skin-tone from lack of oxygen to the tissue - or via blood work), methylene blue would be the "antidote", to restore the ferrous iron and convert methemoglobin back to normal hemoglobin

I think as with all "antidotes", they look at the symptoms that someone presents (existence of methemoglobin), and try to treat that (with MB) if the root cause is unknown and time is important

 

[Stargazer100]

Yes but I read that too much methylene blue at once can also cause homglobin to convert to methemoglobin