Wednesday, August 30, 2006

Hydromorphone vs morphine for severe acute pain in the ED

Per the last post, here's a brief summary of the article. The study compared 0.015mg/kg of IV hydromorphone (1.5mg for a 100kg person) vs 0.1mg/kg IV morphine (10mg for a 100kg person). (They used the HM:M ratio of 1:6.67). Interestingly the background to this was that the authors, besides noticing that pain is often poorly treated in the ED, also noticed that people seemed reluctant to give the established dose of morphine for severe pain. They speculated that if they could promote HM as an effective analgesic, people would be more likely to use it because the milligram dosage is lower. This concept is clearly the theme of Pallimed for August, given this recent post. Sad but true. About 100 people were randomized in this well-blinded trial. It was a single instituion trial and most of the patients were Hispanic. The median pain score was 10/10. Patients receieved 'rescue' analgesia ad lib after the initial 'trial' treatment. Findings were essentially:
1) Hydromorphone decreased pain by 5.5/10 at 30 minutes vs 4.1/10 at 30 mins for morphine. This was borderline significant.
2) Hydromorphone definitely seemed to decrease pain more effectively (compared to morphine) for those with 10/10 pain: decreased by 5.9/10 compared to 3.7/10 at 30 minutes.
3) There was no differences in between groups at 2 hours including those with baseline 10/10 pain
4) Pruritis really did seem to occur more commonly with morphine (6% vs 0% although the numbers are small).
5) No significant adverse or safety problems were noted in this opioid naive population.

My gloss is that this supports the observation that morphine is one of the more pruritogenic opioids out there, and that the analgesic time-profile of morphine may be a little delayed compared to HM (this is not news). Finding #2 is interesting and deserving of investigation. Assuming all 'strong' opioids truly are equally effective analgesically, if this finding is validated it may cause us to tweak our understanding of HM:M potency. Of note, these were opioid naive patients, and extrapolation to the chronic opioid patient is difficult. The real story though is, like the other post, an apparent systematic underdosing of morphine, despite well accepted doses, presumably because 10mg is scarier than 1.5mg. This is a sad, but believable, state of affairs. Perhaps a campaign reassuring our colleagues that equianalgesia is a real thing--honest!--is needed. "Equianalgesia--believe it!" can be our motto. Christian, can you make up a logo?

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