Methoxyflurane inhalation vapour in trauma pain: a profile of its use in the EU

Inhaled methoxyflurane for the management of trauma related pain in patients admitted to hospital emergency departments: a randomised, double-blind placebo-controlled trial (PenASAP study)

BACKGROUND

Oligo-analgesia is common in the emergency department (ED). This study aimed at reporting, when initiated by triage nurse, the superior efficacy of inhaled methoxyflurane plus standard of care (m-SoC) analgesia versus placebo plus SoC (p-SoC) for moderate-to-severe trauma-related pain in the hospital ED.

METHODS

A randomised, double-blind, placebo-controlled trial was conducted at eight EDs. Adults with pain score ≥4 (11-point numerical rate scale, NRS) at admission were randomised to receive one or two inhalers containing m-SoC or p-SoC. Primary outcome measure was time until pain relief ≤30 mm, assessed on the 100-mm Visual Analogic Scale (VAS).

RESULTS

A total of 351 patients were analysed (178 m-SoC; 173 p-SoC). Median pain prior to first inhalation was 66 mm, 75% had severe pain (NRS 6-10). Median time to pain relief was 35 min [95% confidence interval (CI), 28-62] for m-SoC versus not reached in p-SoC (92 - not reached) [hazard ratio), 1.93 (1.43-2.60), P < 0.001]. Pain relief was most pronounced in the severe pain subgroup: hazard ratio, 2.5 (1.7-3.7). As SoC, 24 (7%) patients received weak opioids (6 versus 8%), 4 (1%) strong opioid and 44 (13%) escalated to weak or strong opioids (8 versus 17%, respectively, P = 0.02). Most adverse events were of mild (111/147) intensity.

CONCLUSIONS

In this study, we report that methoxyflurane, initiated at triage nurse as part of a multimodal analgesic approach, is effective in achieving pain relief for trauma patients. This effect was particularly pronounced in the severe pain subgroup.

Inhaled Methoxyflurane versus Intravenous Morphine for Severe Trauma Pain in the Emergency Setting: Subgroup Analysis of MEDITA, a Multicenter, Randomized, Controlled, Open-Label Trial

Purpose

Opioid analgesics remain the cornerstone of treatment for severe trauma pain in the emergency setting, but there are barriers to their use. This post hoc analysis of a previously reported trial (MEDITA) investigated the efficacy and safety of low-dose methoxyflurane versus intravenous (IV) morphine for severe trauma pain.

Patients and Methods

MEDITA was a Phase IIIb, randomized, active-controlled, parallel-group, open-label study in Italian pre-hospital units and emergency departments (EudraCT: 2017-001565-25; NCT03585374). Adult patients (N=272) with moderate-to-severe trauma pain (score ≥4 on the Numerical Rating Scale [NRS]) were randomized 1:1 to inhaled methoxyflurane (3 mL) or standard analgesic treatment (SAT; IV paracetamol 1g or ketoprofen 100mg for moderate pain [NRS 4-6] and IV morphine 0.1mg/kg for severe pain [NRS ≥7]). Analyses were performed for the severe pain subgroup. The primary efficacy variable was the overall change from baseline in visual analog scale (VAS) pain intensity at 3, 5 and 10min post-randomization. Non-inferiority of methoxyflurane versus morphine was concluded if the upper 95% confidence interval (CI) for the treatment difference was <1; superiority was concluded if the upper 95% CI was <0.

Results

Ninety-three patients (methoxyflurane: 49; SAT: 44) were included in the severe pain intention-to-treat population. The reduction in VAS pain intensity over the first 10min was superior for methoxyflurane versus morphine (adjusted mean treatment difference: -5.54mm; 95% CI: -10.49, -0.59mm; p=0.029). Median time to onset of pain relief was 9min for methoxyflurane and 15min for morphine. Patients rated treatment efficacy and physicians rated treatment practicality "Excellent" or "Very good" for more methoxyflurane-treated patients (42.8% and 67.3%) than morphine-treated patients (18.1% and 22.8%). Adverse events, all non-serious, were reported in 20.4% of methoxyflurane-treated patients and in 4.8% of morphine-treated patients.

Conclusion

Methoxyflurane provided superior short-term pain relief to IV morphine in patients with severe trauma pain and offers an effective non-narcotic treatment option.

A Review of the Burden of Trauma Pain in Emergency Settings in Europe

Trauma pain represents a large proportion of admissions to emergency departments across Europe. There is currently an unmet need in the treatment of trauma pain extending throughout the patient journey in emergency settings. This review aims to explore these unmet needs and describe barriers to the delivery of effective analgesia for trauma pain in emergency settings. A comprehensive, qualitative review of the literature was conducted using a structured search strategy (Medline, Embase and Evidence Based Medicine Reviews) along with additional Internet-based sources to identify relevant human studies published in the prior 11 years (January 2006-December 2017). From a total of 4325 publications identified, 31 were selected for inclusion based on defined criteria. Numerous barriers to the effective treatment of trauma pain in emergency settings were identified, which may be broadly defined as arising from a lack of effective pain management pan-European and national guidelines, delayed or absent pain assessment, an aversion to opioid analgesia and a delay in the administration of analgesia. Several commonly used analgesics also present limitations in the treatment of trauma pain due to the routes of administration, adverse side effect profiles, pharmacokinetic properties and suitability for use in pre-hospital settings. These combined barriers lead to the inadequate and ineffective treatment of trauma pain for patients. An unmet need therefore exists for novel forms of analgesia, wider spread use of available analgesic agents which overcome some limitations associated with several treatment options, and the development of protocols for pain management which include patient assessment of pain.Funding: Mundipharma International Ltd.