Opioid Induced Constipation

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Robert D. -

QuestIon: If methyl-naltrexone is given in the ED (SQ or po), how long before an effect/success? Thank you

Sean N. -

Hi Robert,

Thank you for your question.

SQ usually works within 15 to 30 minutes and recommend for ED.

PO can take 2 to 4 hours although could see results quicker.

As above I recommend SQ for patients in ED.

Best regards,


Leslie B., MD -

Very helpful segment, thank you.

Patrick -

When giving oral naloxone do you simply dose the liquid from syringe?
Thank you.

Sean N. -

Hi Patrick,

Yes I dose the liquid from syringe and place in juice for patient

Thank you


Áine Y. -

I was concerned and disappointed to hear the discussion of parenteral naloxone for OIC in the ED. This is a drug with a very narrow therapeutic window for patients on chronic opiates, as you acknowledged. In this modern world where methylnaltrexone exists, I would argue that there should be no role for IV naloxone for OIC in the ED, due to its greatly increased potential for harm to the patient. I will grant that the cost of methylnaltrexone is such that it shouldn't be a first line agent, but for those in whom more conservative measures fail, and an injectable medication is required, this should be the go to agent.

Also, one key element of the evaluation was omitted in this discussion of constipation: the digital rectal exam. Hey, I get it, it's gross, we hate to do it, and we hate to talk about it. But fecal impaction is common, and all the medications in the world won't help if you have left an obstructing stool ball in the rectum. What's more, as any experienced nurse will tell you, direct rectal stimulation alone has a significant therapeutic effect that may obviate the need for any acute medication treatment in the ED. Sadly, the number of times I have seen this element of the exam skipped over -- in a patient with the chief complaint of constipation -- is non-trivial.



William G. -

I long ago lost track of the number of patients turned over to me who GOT AN XRAY but not a DRE and had a Dx of OIC. Rectal exams are essential, especially in the elderly whose muscle tone and CV status make stool effort either weak or dangerous. DRE will tell you if this is a distal colon/rectum issue or, what is more common in OIC, an ascending/transverse colon issue as opiates seem to have a marked slowing effect in the transverse colon. Methylnaltrexone and 10 loving ounces of mag citrate followed by - and this is the important part - 6 oz H2O immediately and every 20 minutes until stool passage - has long been a recipe for success in 15 years of relieving this problem.

Sean N. -

Hi Liam,

Thank you for your comments.

Yes, we agree in the ED we recommend oral naloxone as we discussed over parenteral naloxone. Methylnaltrexone as you mentioned is more expensive but can be used initially.

However, these patients given low dose parenteral naloxone generally do not have reversal of analgesia or withdrawal.

I have worked with several acute pain anaesthesiologists that use low dose continuous naloxone infusions with patients on opioid patient controlled analgesia to minimize opioid-related adverse effects eg, pruritis, nausea, urinary retention, constipation without reversal of analgesia. See one study below at bottom of page.

Regarding the DRE and disimpaction completely agree with you that this may be required but would recommend less invasive medication approach initially as for many of these patients this can be a recurring problem that can be treated with medications and then with appropriate bowel regimen.

Remember the old saying "the hand that writes the opioid prescription without an appropriate bowel regimen should be the hand to disimpact" emphasizing the need for good bowel regimen when prescribed and when discharged from ED after treatment for opioid-induced constipation.

Best regards,

Anesth Analg. 2005 Apr;100(4):953-8.

The effects of a small-dose naloxone infusion on opioid-induced side effects and
analgesia in children and adolescents treated with intravenous
patient-controlled analgesia: a double-blind, prospective, randomized,
controlled study.

Maxwell LG(1), Kaufmann SC, Bitzer S, Jackson EV Jr, McGready J, Kost-Byerly S,
Kozlowski L, Rothman SK, Yaster M.

Opioids are frequently associated with side effects such as nausea, vomiting,
and pruritus. We hypothesized that a prophylactic, continuous small-dose
naloxone infusion would reduce the incidence of opioid-induced side effects
without affecting analgesia or opioid consumption. In this prospective,
double-blind, randomized, controlled clinical trial, we studied 46 postoperative
patients (M:F, 21:25), averaging 14 +/- 2.5 yr and 53 +/- 17 kg, at the start of
morphine IV patient-controlled analgesia. Patients were randomized to either
saline (control, n = 26) or naloxone 0.25 microg . kg(-1) . h(-1) (n = 20). We
found that the incidence and severity of pruritus (77% versus 20%; P < 0.05) and
nausea (70% versus 35%; P < 0.05) was significantly more frequent in the placebo
group compared with the naloxone group. Morphine consumption (1.02 +/- 0.41 mg .
kg(-1) . d(-1) versus 1.28 +/- 0.61 mg . kg(-1) . d(-1)), pain scores at rest (4
+/- 2 versus 3 +/- 2), and pain scores with coughing (6 +/- 2 versus 6 +/- 2)
were not different. We conclude that, in children and adolescents, a small-dose
naloxone infusion (0.25 microg . kg(-1) . h(-1)) can significantly reduce the
incidence and severity of opioid-induced side effects without affecting
opioid-induced analgesia. When initiating morphine IV patient-controlled
analgesia for the treatment of moderate to severe pain, clinicians should
strongly consider starting a concomitant small-dose naloxone infusion.

DOI: 10.1213/01.ANE.0000148618.17736.3C
PMID: 15781505 [Indexed for MEDLINE]

tom f. -

thank you so very much for this pod Sean, and
the EMrap team also.
I did not know before now much of what you discussed here. excellent .

some thoughts.. as you made clear, never assume anything, and certainly in a case of an patient coming to the ED complaining of abdominal pain, and "constipation", one must not , as Swami stated, stop thinking , and just assume that that is all it might be, especially in any older patient, and /or one with cancer. abdominal pain in the elderly is a potential time bomb. (and you stated this in the pod). I have a low threshold to CT scan (I find most abdominal plain films useless) if there is any doubt that this is clearly only opioid-induced constipation.

I sometimes resort to the four liters of PEG (eg, "go-lytely", or equivalent) in more difficult cases, sometimes with a script, with instructions that the patient need not use the whole four liters, just till reasonable success. I guess it's a mega-blast of 17 gms of miralax.

again, thank you for an excellent pod. Sean, I have been listening to your pods for years, and its always a pleasure.

Sean N. -

Hi Tom,

Glad you enjoyed and thank you for the comments

PEG-ELS (GoLytely) can be used

I have found the nausea associated with opioid-induced constipation can be the limitation of PEG-ELS because of the volume eg 4 liters causing distention but just as you do and I would agree would not need to use the whole 4 liters if effective and is safe option for home use when discharged

MirLax being OTC and less volume usually a bit better tolerated but for sure can try PEG-ELS

Best regards,

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EM:RAP 2021 February SNACK: Opioid-Induced Constipation Full episode audio for MD edition 13:43 min - 15 MB - M4A