# Penthrox



## Nova1300 (Nov 4, 2015)

Heard about it for the first time today.

And I'm absolutely fascinated.  

For those who have used it in practice-
Did you find it to be an effective analgesic?
Did you have to deal with any nausea?
Any changes in hemodynamics? 
Did you have any protocols for use in asthma? 
Did you use it conjunction with opiates? 
What were the hard contraindications? 


I really think I like the concept. Maybe?  I'm a little surprised by the potent analgesic effects.  

Feed my curiosity...


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## chaz90 (Nov 4, 2015)

@Clare

I believe Clare uses it in New Zealand, but I know nothing about it. I'm curious as well though, so I'd certainly like to see where this goes!


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## triemal04 (Nov 4, 2015)

Heard of the Aussies (and Germans?  Maybe?  Or they used/used to use an inhaled anesthetic of one type or another) using the Penthrox devices but obviously have never used one myself.

What I have used is nitrous, which, when used in the right circumstances, can be very effective.  And, apparently the nitronox system is once again being manufactured.  http://www.porterinstrument.com/product/dental/Nitronox Field Unit  Not the best, but it used to be a decent system for what it was.


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## Nova1300 (Nov 4, 2015)

You know, nitrous is amazing in many ways.  And I think it definitely has utility. 

We don't use methoxyflurane in the states, so I never really learned much about it.  Most of the anesthetic gasses do not offer much in the way of analgesia.  I actually had no idea methoxy did. 

What I find really shocking is the MAC of methoxyflurane is very low.  Meaning, basically, a little bit goes a long way.  And it is a respiratory depressant.  But they seem to use it across the pond without much trouble.


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## EpiEMS (Nov 4, 2015)

Nova1300 said:


> You know, nitrous is amazing in many ways.  And I think it definitely has utility.
> 
> We don't use methoxyflurane in the states, so I never really learned much about it.  Most of the anesthetic gasses do not offer much in the way of analgesia.  I actually had no idea methoxy did.
> 
> What I find really shocking is the MAC of methoxyflurane is very low.  Meaning, basically, a little bit goes a long way.  And it is a respiratory depressant.  But they seem to use it across the pond without much trouble.



Are clinical indications for use of methoxyflurane any different than nitrous? Curious if the former is used anywhere in the U.S. (I haven't come upon it in any protocols I've read through), as it seems to be widely used in the Commonwealth countries even at the BLS level (while nitrous is AEMT-scope in the States).


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## SandpitMedic (Nov 5, 2015)

Man oh man! I love the stuff! It is in our formulary here in the UAE. My largest encounter with it was when I used them about 6 times in one night when we had a mass casualty. Doc was running around with a drop leg pouch full of the stuff. We just open it up and poor it into the inhaler "whistler" and tell the pt to start sucking. They worked great. I only had one pt c/o nausea, but other than that there were no issues. As far as I'm concerned it should be used in the US... It is self limited... They hold it and suck on it until it kicks in enough that they lack the ability to hold it in their own mouth. It's perfect and works like a charm.

We also carry Nitrous Oxide called Entonox for moderate to severe pain. It is a great drug also, and serves its purpose well. The delivery system is similar to an O2 with CPAP, except no mask... basically, they hold the mouth piece (or you do if you want) ad as they inhale it draws from the cylinder. Both are very short acting (30-60 second onset) and have a very short duration once stopped. Oh, and you can't really OD... Wonderful.

These drugs are in common usage all around the world. It is a wonder we don't use it in the USA. In other countries, the use of narcotics is sometimes challenging (yes, even for medical purposes) and this is the main reason we use it here in the Middle East. In my opinion, the more tools in the box the better, especially since opiate addiction in relation to pain management in the USA is becoming a hot topic with a lot of ethical and moral debates about the use of opiates.


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## Nova1300 (Nov 5, 2015)

We stopped using it in anesthesia because it can be nephrotoxic at anesthetic doses.  

There are a few studies on pubmed looking at penthrox for procedural sedation, for which it appears to be both safe and efficacious.  

There is also an abstract from a journal called Human Experimental Toxicology which was published in April of this year.  It looks like it may be some sort of meta-analysis looking at nephrotoxicity with penthrox, which is given in far lower doses than those used for general anesthesia.  Unfortunately, my institutional account will not let me access the full text.  But, the abstract would suggest that the nephrotoxicity potential in these doses is negligible.  

Aside from the historical nephrotoxicity at general anesthetic doses, does anyone know any other reasons we don't have this stuff?


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## akflightmedic (Nov 5, 2015)

Used penthrane for years in Afghanistan. I know we have to worry about the toxicity, however when they are self administering it is literally impossible for them to overdose. They are fun to watch. Their hand drops and they cannot raise the inhaler to their mouth. They gesture, they move their lips, but the concept is simple...if you cannot raise the inhaler, then you do not need the drug. LOL


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## akflightmedic (Nov 5, 2015)




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## akflightmedic (Nov 5, 2015)

I had to black out his face so no one complains despite him being long dead...


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## DPM (Nov 5, 2015)

I'm sure some of the U.K. Folk will have more info on Nitro, but years ago I heard about an interesting BLS Chest pain protocol with entonox in it. Granted this was back in the hi-flo O2 days, but suspected cardiac chest pain got ASA and Entonox. The mix still gave an FiO2 of around 50% (to satisfy the hi-flo argument) and the analgesia helped reduce anxiety, reducing heart rate and strain on the heart.  

I also saw entonox used once on a poor fella who'd come off of a motorbike. It was years ago, but he seemed to enjoy it and didn't seem to complain too much about his angulated lower leg!  

Methoxyflurane is a BLS drug in Australia. I saw lifeguards using the "green whistle" quite a few times.


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## Nova1300 (Nov 5, 2015)

Im curious about the price difference too.  Medical gasses, including nitrous, tend to be expensive.  

Surely more expensive than a few cc's of methoxyflurane and a plastic tube.  

As someone who grew up with a broad scope of pain control options, including morphine . . . and the second tubex of morphine, I can only imaging how great this device must be if it really is an effective analgesic.


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## EpiEMS (Nov 5, 2015)

akflightmedic said:


> I had to black out his face so no one complains despite him being long dead...



Well, he looks happy as a clam with the green whistle."

Have you ever observed patients having an adverse reaction to penthrane?


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## DPM (Nov 5, 2015)

Nova1300 said:


> Im curious about the price difference too.  Medical gasses, including nitrous, tend to be expensive.
> 
> Surely more expensive than a few cc's of methoxyflurane and a plastic tube.
> 
> As someone who grew up with a broad scope of pain control options, including morphine . . . and the second tubex of morphine, I can only imaging how great this device must be if it really is an effective analgesic.



A quick Google search finds single doses + green whistle retail at $45 Australian, so $36 US. And that's for a single unit. Definitely not cost prohibitive.


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## Clare (Nov 6, 2015)

At Emergency Medical Technician level in New Zealand we have entonox, methoxyflurane, paracetamol, ibuprofen and tramadol  

I have never personally administered methoxyflurane.  We carry it either as an alternate to entonox (if it is contraindicated) or where physically carrying entonox is not practical.  To my knowledge, every one of the state ambulance services in Australia have ditched entonox and replaced it with MOF.  It is also used by one of our tertiary burn units.  

Entonox is our main "go-to" starting analgesic and it's great stuff.  I would simply refuse to work without it.  A single tank holds several hundred litres (it is the same size as our portable oxygen) so is reasonably portable, is simple to administer (patient just has to suck the mouthpiece, and the mouthpiece is the only consumable that needs changing), works wonders and last ages.  Entonox is awesome for getting people's pain under control while we get a drip into them to administer morphine (or fentanyl and is often all that we need to administer to get their pain down to a tolerable level - although paracetamol, ibuprofen and tramadol are also good for that if their pain is not "bad' enough.

I have never seen or heard anybody say anything about a bad reaction to MOF as an analgesic.


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## EpiEMS (Nov 6, 2015)

Clare said:


> At Emergency Medical Technician level in New Zealand we have entonox, methoxyflurane, paracetamol, ibuprofen and tramadol


Insightful as always, Claire, thanks! Curious -- are your EMT administered pain control meds all PO?


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## Nova1300 (Nov 6, 2015)

Great info Clare, thank you!


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## Carlos Danger (Nov 6, 2015)

Interesting. I've never heard of methoxyflurane either, outside of the few times I've seen it mentioned on this forum. Sounds pretty awesome.

I've also never understood why prehospital nitrous isn't more common in the US. I've never seen it outside the OR.


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## DPM (Nov 6, 2015)

Remi said:


> Interesting. I've never heard of methoxyflurane either, outside of the few times I've seen it mentioned on this forum. Sounds pretty awesome.
> 
> I've also never understood why prehospital nitrous isn't more common in the US. I've never seen it outside the OR.



When I've asked I've had a few responses. 

One: it is hard to account for how much is used, both for billing and for accountability (because obviously we're all going to use it.)

Second: storage of mixed gases, regulators, and other things that didn't make sense or weren't accurately explained to me. Whe I brought up that other countries use it I got the "well their rules are different over there" line. 

Third: ventilation and exhaust issues causing  second hand entonox exposure for the attendant. Again, despite the fact that other countries have overcome this, their methods were unacceptable for the US. 

I think these reasons are BS. Gas and air is almost 100 years old, and methoxyflurane has been around since the 70's. These aren't insurmountable obstacles, but if we can't switch from Morphine to Fentanyl then I'm not going to hold my breath for these drugs either...


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## Carlos Danger (Nov 6, 2015)

akflightmedic said:


> I had to black out his face so no one complains despite him being long dead...



HIPAA never dies.


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## gotbeerz001 (Nov 6, 2015)




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## akflightmedic (Nov 6, 2015)

Well technically I come no where near violating HIPAA....seeing as how I did not bill for the patient, I did not transmit any of his personal information electronically, in fact I only have his ONE name which is very common and an assigned birthday. Just sayin... 

Almost every Afghan "in the system" has a birthday of January 1 and an estimated year based on their recollection of how many seasons have passed or any major events which occurred during their birth year and shared with them by their parents or elders.


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## gotbeerz001 (Nov 6, 2015)

HIPAA Hippo was kidding. 
He just thinks he's cute.


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## EpiEMS (Nov 7, 2015)

akflightmedic said:


> Almost every Afghan "in the system" has a birthday of January 1 and an estimated year based on their recollection of how many seasons have passed or any major events which occurred during their birth year and shared with them by their parents or elders.



That's fascinating! Must make for some interesting discussions!


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## SandpitMedic (Nov 8, 2015)

They don't typically speak English... I'm not too sure about AK's experience in Afg, but my experience with non English speakers and local Arabic translators...is almost just as bad. Lol, at least my patients have birthdays though.


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## DPM (Nov 8, 2015)

I typically had Taliban, who got a prisoner tag, or ANSF who had some kind of ID usually.


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## jwk (Nov 8, 2015)

I don't believe MOF is commercially available in the US - as I recall, Australia is the only developed country in the world where it's commonly used.  It is in fact nephrotoxic, which in the US means it's dead from a medicolegal standpoint (meaning plaintiffs lawyers would be all over it).  It had very limited use in anesthesia even when it was available, and I haven't seen it in the OR in about 25 years.


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## auseventmedic (Nov 9, 2015)

We use it all the time in australia, really good drug for pain relife works well with trauma and  musculoskeletal injuries we give it in 3mls max of 6ml is grate for kiddies as you do not need to use a needle or cannular and we also use it with opiates


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## DPM (Nov 9, 2015)

jwk said:


> I don't believe MOF is commercially available in the US - as I recall, Australia is the only developed country in the world where it's commonly used.  It is in fact nephrotoxic, which in the US means it's dead from a medicolegal standpoint (meaning plaintiffs lawyers would be all over it)...



There are a few studies that disagree about the side effects. 

http://onlinelibrary.wiley.com/doi/...ionid=9543629926D846CA6C5E76AD9B42E1FD.f03t01

http://onlinelibrary.wiley.com/doi/10.1111/j.1742-6723.2006.00874.x/abstract

Unfortunately, they're "non-US" studies, so we'd probably have to wait for a US trial.


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## jwk (Nov 9, 2015)

You'll never


DPM said:


> There are a few studies that disagree about the side effects.
> 
> http://onlinelibrary.wiley.com/doi/...ionid=9543629926D846CA6C5E76AD9B42E1FD.f03t01
> 
> ...


Doubt you'll ever see it in the US again.  There's absolutely zero commercial interest in it and it's no longer FDA approved.  Nobody is or will be interested in attempting to bring it back to market due to the potential side effects, so it would never be a commercially viable product.  Far better agents have come to market in the ensuing years, and no new agents have been developed in more than 40 years.


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## DPM (Nov 9, 2015)

I'm not necessarily pushing for penthrox, but I think we should have entonox. Non opiate pain relief should be a priority, considering that the US has more opiate addicts than the rest of the world combined.


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## triemal04 (Nov 9, 2015)

DPM said:


> I'm not necessarily pushing for penthrox, but I think we should have entonox. Non opiate pain relief should be a priority, considering that the US has more opiate addicts than the rest of the world combined.


........we DO have entonox.  All entonox is, is a premixed bottle of nitrous and oxygen; the FDA prohibits that and requires a blender to be used.  But, just like in a dentists office or OR there is a portable version that can easily be used, the nitronox setup.  And no, I'm not a shill for the company.

The problem is that nitronox and any other system is kind of unwieldly, and more importantly, in the US we often have a bad case of rectocranial inversion and can't recognize a different but good thing.


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## Nova1300 (Nov 10, 2015)

Unfortunately I think jwk is right.  Getting methoxyflurane back, in any formulation, into the states is probably going to be very difficult. 

I would argue one point he made, though: That far better agents have come to market in recent years.  This is true.  The newer anesthetic agents are better suited for providing surgical anesthesia for a myriad of reasons. 

But methoxyflurane is unique in its analgesic properties, something the other agents lack.  And if it can be shown to do that safely at sub-anesthetic doses in a patient-controlled device, that would be effective in all patients regardless of chronic opiate use or medical history, that was short acting, relatively inexpensive, and had very little nausea, it seems to me it might be a rather ideal agent for use in the prehospital environment.  

I can't really think of any pain control mechanism currently in use in ems for which I can say all of those things are true.


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