IV Paracetamol vs morphine for pain

Craig M, Jeavons R, Probert J, Benger J. Randomised comparison of intravenous paracetamol and intravenous morphine for acute traumatic limb pain in the emergency department. Emergency Medicine Journal 10.1136/emj.2010.104687 PMID 21362724

I confess I have a bias against this stuff. Putting paracetamol in a bottle and charging massive amounts for it is quite the marketing move but I have yet to be convinced. It used to always annoy me when I saw docs prescribing this as some sort of placebo for proper pain meds (ie opiates) beacuse the nurses would hang it and the doc wouldn’t have to go to the patient’s bedside themselves and give it. (in the place I sued to work the docs had to give IV morphine, crazy I know…)

One of the bosses even tried to put a kind of ban on it for being overused and overpriced.

But now there’s stuff coming out to try and point me the other way. Like this trial.

METHODS

  • RCT, blinded, non-pharma funded
  • pain >7/10 with isolated limb trauma were eligible
  • radomised to 1g IV paracetamol over 15 mins or 10mg IV morphine (a reasonable dose) over 15 mins.
  • morphine was rescue for both groups if needed
  • outcome was pain on a VAS

RESULTS

  • n = 55 so tiny numbers which is the single biggest problem
  • paracetamol group had consistently higher pain (about 6mm) but it decreased in the same manner as the morophine group and they were of comparable efficacy
  • neither group did that well (pain went from 75 to 55 over an hr) and 1/3 in each group wanted resuce meds
  • they state a statistically significant increase in AEs in the morphine group but this was 8 vs 2 pts and they don’t tell us specifically what those AEs were
  • more pts were satisfied in the morphine group

They conclude that a large trial is needed to answer this, and it seems that it probably does. This one is two small to change practice over. Especially when it involves something almost 10 times the price.

My bias is that I’ll want morphine when I break my arm, and that remains unchanged for now, but as always I’m willing to be persuaded!

The thing I get concerned with, is that people would read this and feel justified in giving paracetmol as appropriate analgesia and forget the more important part of going back and reassessing and offereing more if they need it

 

NB EM Lit of Note had a similar post a few weeks back on the same topic. Go read it.

About Andy Neill

EM Reg/Resident based near Dublin. Former anatomy lecturer, theology student and occasional musician @andyneill | + Andy Neill | Contact

Comments

  1. I would have added a third arm to this study -- a placebo group….

  2. Withholding analgesia when someone needs it. Ethically dodgy, no?

  3. really the best thing for your “broken arm” is regional anesthesia, in most cases…but i realize EM is there yet

    if the price were better and it was available to me, i would be using BOTH morphine and paracetamol in traumatic injuries.

    however, i agree with you: a repeat trial with huge numbers would be nice

    and one that includes subset analysis pulling out fractures
    —-
    btw, i am new to this blog recently -- great stuff -- i am adding it to my list of frequent reads, which includes the biggies like LITFL and EM Crit, and SMART EM, etc.

    keep going (i especially like the anatomy reviews with clinical references)

    HH

    • Hi Hamhock, thanks for the comments. Totally agree, no need to have just one agent when we can have two (though not if we cripple the bank account) and it would have been particularly appropriate in this study where neither group got especially good pain relief

  4. Personally I also have a huge bias against iv paracetemol. Everywhere I have read it is recommended for mild to moderate pain only. The use in severe pain makes no sense to me. Thats why we have morphine which in my hospital is about 25% of the cost of iv paracetemol (1g vs10mg) not to mention the cost of the giving set to infuse it ( not sure how that compares to the total cost of a needle / syringe and 10ml normal saline vial to give the morphine but assume a little more)

    The big issue is most of the juniors using the drug have no idea of relative cost or bioavailability. Sure iv paracetemol has peak effects in 15 minutes but oral its only an hour to reach therapeutic levels to no major difference there. The only thing I would say is I would be loathe to use pr paracetemol in isolation due to its erratic absorption taking many hours to achieve peak concentration.

    For those who don’t know iv paracetemol costs about 6 euro per 1g vial while pr is about 1.5 euro. Oral paracetemol however is only about 3 cents for 1g and also avoids the expensive giving set so probably the cost diffence between oral and iv paracetemol is at least 200 if not 300 times that of the oral dose.

    For the record my preference is morphine titrated to presentation, not always a lover of the pain score but can at least titrate to comfort and often I’ll give pr diclofenac (obviously not in all patients) +/- paracetemol po or pr ( though less of a fan of pr nowadays) about the same time as the iv is given for maximum effect.

    • Thanks for the comments adrian

      I’ve rarely given PR dicolfenac but it does have a reputation for being an excellent analgesic. I definitely like the idea of giving more than one analgesic and giving it till the patients comfortable

    • > I would be loathe to use pr paracetemol in isolation

      Loath or Loathe?

      Loath is an adjective meaning “unwilling.” It ends with a hard th and rhymes with growth or both.

      Loathe is a verb meaning “to hate intensely.” It ends with a soft th like the sound in smooth or breathe.

      Examples: He was loath to admit that he was included in the deal.
      (He was unwilling)

      Alex loathes spiders.
      (Hates them intensely)

    • Rachel smalley says:

      My name is Rachel smalley
      I’m from Lincoln
      I’ve chronic pancrentitis and I need it to b taken away all of it I’ve had morphine for the hurendus pain I’ve had medicine pets coned KETTERMINE EPIDURALS EVEN and nothing NOTHING has totallystopped my chronic pain as much as a simple paracetamol IV drip so I’m for it ALL THE WAY

  5. I’m a fan of Ed Gentile’s morphine protocol myself (as described on EMRAP and EMCRIT) http://emcrit.org/podcasts/gentile-pain/
    Particularly for things like renal colic or fractures.

  6. Andy Pigott says:

    This is very interesting study. I have done a fair bit of investigating in regards to pre-hospital analgesia. The major problem I found with this particular article was the rigidity of the dosage protocols. It is well documented that morphine should be given at a 0.1 mg/kg (although some studies explore that 0.15 to 0.2mg/kg is safe and effective), by giving everyone 10mg of morphine you are assuming every patient is 100 kg -- a tad on the chunky side you may agree. Similarly with Paracetamol the BNF advises a dose of 15 mg/kg for paracetamol to most effective. A dose of 1g under doses the average patient -- especially when it has been shown that an initial dose of up to 2g does not produce a plasma level in the toxic range.
    So in this study Morphine in over dosed and paracetamol is under dosed -- not the high quality unbiased evidence that is appears to be.
    When considering the use of IV paracetamol for acute/ emergency pain management there is very little good (high quality RCT) evidence supporting its use. Although the evidence that is available is showing at the very least equivalency to morphine. Which is very promising when you consider the side effect or morphine/ opioid analgesics of respiration depression.
    What is required is a weight dose linked RCT comparing the two drugs. Also a trial looking at combination treatment as I have had some very promising results when combining the two analgesic for extremity trauma!
    In my opinion IV paracetamol is underused but a wonderful alternative to opiates
    Andy

    • i’ve heard the 15mg/kg for oral dosing but i don’t know of much data on weight based dosing for IV paracetamol. I’m becoming a convert to the role of paracetamol IV but my concern is that it will be used instead of opiates when opiates AND paracetamol may be better.

  7. Hi, I’m a paramedic with SECAMB in the UK. Our critical care paramedics have been using IV PARACETAMOL for a few years now with great success. They also have ketamine. Because it is so effective it has been rolled out to all paramedics in SECAMB. A few other services also have it. Personally I have used it many times and think it’s great. As part of a multi modal analgesic approach in trauma or as a stand alone or alternative analgesia in medical patients it really is good stuff. Septic patients in pain, painful post op infections etc etc. Morphine isn’t always the most appropriate analgesic. Cheers

    • I am slowly becoming more persuaded on the IV paracetamol, though I wouldn’t want it to be given instead of morphine -- something that happens a lot in EDs where it’s easier to give IV paracetamol than morphine

  8. The 2 together work really well in trauma. Still give opiates of course. But as you know we don’t turn have to give quite so much opiate if given in conjunction with IV paracetamol

  9. Just dropping my mum off for a knee replacement and interested to be told that IV paracetamol used routinely rather than morphibe post op. Will be interested to see how works!

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