Self-administered inhaled painkiller shows superiority in prehospital setting

A new study has revealed an inhaled analgesic recently introduced to the UK is the most effective form of severe pain relief in the prehospital setting following traumatic injury, in terms of speed of pain reduction.1

Treatment during the first hour after trauma is vital to improve patient survival and good analgesia can result in easier injury management and the potential to avoid chronic pain development.2,3 Despite this, less than a third of people in UK ambulances are given appropriate pain relief.4

The year-long MAPIT study, led by Professor Aloysius Niroshan Siriwardena of the University of Lincoln, UK, and carried out by East Midlands Ambulance Service, showed that the analgesic Penthrox®▼ (methoxyflurane), acts more than three times quicker than the most frequently used – and also inhaled – analgesic, Entonox® (gas and air), more than three times quicker than intravenous paracetamol, and twice as quick as intravenous morphine to reduce severe pain.1

Methoxyflurane, which has been dubbed the ‘green whistle’ has already been proven to be a convenient and effective option for pain relief, leading to a significant reduction in time spent in the hospital emergency department. Although it is used regularly in UK emergency departments, it is not widely used in ambulances.5-8

The data from the MAPIT study, was, on 23 March, shared at the 999 EMS Research Forum Annual Conference, providing the first comprehensive UK comparison of analgesic options used by paramedics and emergency medical technicians.1 The evidence means prehospital emergency staff can now feel confident when choosing methoxyflurane as a first-line treatment option for moderate-to-severe trauma pain.

Rapid and effective pre-hospital analgesia has the potential to improve the patient journey end-to-end. With the NHS continuing to face an exceptional crisis following the outbreak of COVID-19 and unprecedented levels of pressure to free up resources across all treatment settings, the study results are welcome news.1-3

Chief Investigator, Professor Aloysius Niroshan Siriwardena, said, “There are many barriers to adequate pain relief. This study is the first to compare methoxyflurane with all other commonly used analgesics in the prehospital setting and the superior results add to the weight of positive findings from other UK and European hospital studies.

“From an academic perspective, it is an important addition to the evidence, and we look forward to seeing how greater uptake impacts patients in other ambulance trusts.”

Dr Leon Roberts, Medical Director for East Midlands Ambulance Service NHS Trust, which carried out the study, said, “Rapid and effective pain relief is undeniably important in the prehospital setting and this study shows that emergency care staff have access to a well-tolerated treatment, which is easy to administer. EMAS is proud to be a leading organisation in prehospital research collaborating with key partners such as the University of Lincoln, who has analysed and evaluated this data.”


1. Smith M, Rowan E, et al. Evaluation of the effectiveness and costs of inhaled methoxyflurane versus usual analgesia for prehospital injury and trauma. Presented at 999 EMS Research Forum Annual Conference, March 2021

2. Chambers J, Guly H. The need for better pre-hospital analgesia. Archives of Emergency medicine. 1993;10: 187-192

3. Friesgaard K, Riddervold I, et al. Acute pain in the prehospital setting: a register-based study of 41,241 patients. Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine. 2018;26(53)

4. Siriwardena AN, Shaw D, Bouliotis G. Exploratory cross-sectional study of factors associated with pre-hospital management of pain. J Eval Clin Pract 2010; 16(6): 1269-75.

5. Fabbri A, Ruggiano G, Garcia Collado S, et al. Role of inhaled methoxyflurane in the management of acute trauma pain. J Pain Res 2020;13:1547-55.

6. Porter KM, Siddiqui MK, Sharma I, Dickerson S, Eberhardt A. Management of trauma pain in the emergency setting: low-dose methoxyflurane or nitrous oxide? A systematic review and indirect treatment comparison. J Pain Res. 2018;11:11-21.

7. Xia AD, Dickerson SL, Watson A, Nokela M, Colman S, Szende A. Evaluation of pain relief treatment and timelines in emergency care in six European countries and Australia. Open Access Emerg Med. 2019;11:229-40.

8. Young L, Bailey G, McKinley J. Service evaluation of methoxyflurane versus standard care for overall management of patients with pain due to injury. Adv Ther. 2020;37(5):2520-2527.