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56 Subgroup analysis of time to first pain relief and rescue medication use in patients with severe acute trauma pain receiving low-dose methoxyflurane analgesia
  1. F Coffey1,
  2. K Mirza2,
  3. M Lomax3
  1. 1DREEAM: Department of Research and Education in Emergency Medicine, Acute Medicine and Major Trauma, Nottingham University Hospitals NHS Trust, UK
  2. 2Accident and Emergency Department, Colchester Hospital University Foundation NHS Trust, Colchester, UK
  3. 3Mundipharma Research Limited, Cambridge, UK


Aim We performed a subgroup analysis of a previously reported randomised, double-blind, placebo-controlled study of low-dose methoxyflurane analgesia for the treatment of acute trauma pain in UK Emergency Departments [STOP!].1,2

Method At triage, patients aged ≥12 years (n=300) with a pain score of 4–7 on the Numeric Rating Scale (NRS) were randomised 1:1 to methoxyflurane (up to 6 mL) or placebo (normal saline). Study medication was self-administered by the patient using a Penthrox® inhaler. Rescue medication (paracetamol/opioids) was available immediately upon request. Adverse events (AEs) were recorded from enrolment until discharge, and at Day 14±2. Analyses of time to first pain relief, time to request for rescue medication and AEs were performed in a subgroup of patients with severe pain (NRS=7) at baseline (n=133).

Results Median time to first pain relief was significantly shorter with methoxyflurane than placebo (3 min versus 5 min, hazard ratio: 2.21; 95% CI: 1.45 to 3.37; p=0.0002). The proportion of patients who requested rescue medication was significantly lower in the methoxyflurane group (9.7%) than the placebo group (32.4%), with a significantly longer time to request for rescue medication in the methoxyflurane group (hazard ratio: 0.19; 95% CI: 0.08 to 0.48; p=0.0004). AEs (mostly mild, transient dizziness and headache) were reported by 50.0% of methoxyflurane patients and 42.3% of placebo patients.

Conclusion Low-dose methoxyflurane administered via the Penthrox® inhaler provides effective analgesia in adult and adolescent patients presenting with severe acute trauma pain.


  1. . Coffey F. Emerg Med J2014;31:613–8.

  2. . Coffey F, et al. Adv Ther2016;33:2012–31.

References®: PENTHROX is a registered trademark of MDI Limited.

Conflict of interest Frank Coffey was paid travel and subsistence expenses by MDI for one investigator’s meeting. Mark Lomax is an employee of Mundipharma Research Limited. There were no other competing interests.

Funding The study was funded by Medical Developments International (MDI) Limited. Karen Mower (Scientific Editorial) provided medical writing services on behalf of Mundipharma Research Limited.

This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See:

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