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NCT Number: NCT07445737

Use of the Methoxyflurane as Pain-killer in the Prehospital Management of Acute Myocardial Infarction

* Chest pain is the main symptom of acute myocardial infarction. A precocious analgesic treatment is justified by patient's comfort and unfavorable hemodynamic consequences of persistent pain. Morphine is the painkiller historically prescribed in this situation. Morphine has never been evaluated vs placebo and is strongly suspected to decrease oral anti-platelet efficacy. Then, morphine has been downgraded, in the 2017 European guidelines (European Society of Cardiology - ESC) from I to IIa. To find alternative treatment is required. * The methoxyflurane is an anesthetic gas used in emergency setting for about twenty years. It is now commonly used in France. Its analgesic properties have been demonstrated. Its main advantages are its maneuverability as it is delivered by inhalation, i.e. without (before) any venous access and self-administered by the patient. Tolerability is good. It could be an excellent alternative to morphine.

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Key information

Conditions

STEMI - ST Elevation Myocardial Infarction Cardiovascular Diseases Chest Pain Heart Diseases Infarction Ischemia Myocardial Infarction Myocardial Ischemia Necrosis Neurologic Manifestations Pain Pathologic Processes Pathological Conditions, Signs and Symptoms ST Elevation Myocardial Infarction Signs and Symptoms Vascular Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 3

Primary location

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Patient age ≥ 18 years
  • Patient managed in pre-hospital setting for a ST elevation myocardial infarction (STEMI) : Chest pain < 12 hours with moderate to severe pain (VAS > 6/10) or STEMI on ECG according to 2017 ESC guidelines

Exclusion criteria

  • Previous analgesic treatment for this episode of chest pain
  • Hypersensitivity to morphine, methoxyflurane, any fluorinated anesthetic or any of the excipients listed in SmPC,
  • Decompensated respiratory failure (in the absence of artificial ventilation),
  • Severe hepatocellular insufficiency (with encephalopathy),
  • Acute head trauma and intracranial hypertension in the absence of controlled ventilation,
  • Uncontrolled epilepsy,
  • Treatment with buprenorphine, nalbuphine and pentazocine, naltrexone, nalmefene or sodium oxybate,
  • Breastfeeding, in case of initiation or continuation after birth of a long-term treatment.
  • Known malignant hyperthermia or genetic predisposition of the patient.
  • History of serious adverse effects of the patient or his family after administration of inhaled anesthetics.
  • History of signs of liver damage after use of methoxyflurane or after anesthesia with a halogenated hydrocarbon.
  • Clinically significant renal impairment.
  • Known renal failure with creatinine clearance below 30 ml/min or undergoing extracorporeal renal replacement therapy.
  • Altered level of consciousness due to any cause, including head trauma, drug or alcohol use.
  • Clinical evidence of cardiovascular instability (PAS <90 mm Hg).
  • Clinical evidence of respiratory depression.
  • Incapacity to self-assess pain intensity
  • Incapacity to methoxyflurane self-administration
  • Known pregnancy, breastfeeding, minors or incapacity (curatorship or guardianship)
  • Participation in another interventional study involving human participants or being in the exclusion period at the end of a previous study involving human participants
  • Absence of a Social Security

Treatment and study plan

Methoxyflurane

Drug

Patient's self-administration of methoxyflurane (Penthrox®) with dedicated inhaler Initial dose: 3 mL (1 vial). A second 3 mL dose can be used. Treatment: from inclusion to hospital arrival.

Other names: Penthrox®

Morphine

Drug

Morphine intra-venous infusion: 3 mg bolus repeated every 5 minutes until obtaining VAS ≤ 3. Treatment: from inclusion to hospital arrival

Primary outcomes

  1. Demonstrate that methoxyflurane self-administered by the patient is at least as efficient in achieving pain relief that morphine

    Time frame: at 30 minutes

    To demonstrate that methoxyflurane self-administered by the patient suffering chest pain related to an acute myocardial infarction is at least as efficient in achieving pain relief that morphine with better tolerance (achieving pain relief, i.e. pain intensity score on visual analogic scale (VAS) ≤ 3 at 30 minutes)

Secondary outcomes

  1. Compare the impact of the treatments on heart rate

    Time frame: at 30 minutes

    Impact of the treatments on cardiovascular system: heart rate (data collected every 5 minutes until to 30 minutes after randomisation and at hospital arrival)

  2. Compare the impact of the treatments on arterial blood pressure

    Time frame: at 30 minutes

    Impact of the treatments on cardiovascular system: arterial blood pressure (data collected every 5 minutes until to 30 minutes after randomisation and at hospital arrival)

  3. Compare the impact of the treatments on pulse oximetry

    Time frame: at 30 minutes

    Impact of the treatments on cardiovascular system: pulse oximetry (data collected every 5 minutes until to 30 minutes after randomisation and at hospital arrival)

  4. Compare the impact of the treatments on ECG

    Time frame: at 30 minutes

    Impact of the treatments on cardiovascular system: ECG changes before discharge from the ambulance

  5. Compare tolerance of the treatments on respiratory depression

    Time frame: at 30 minutes

    Tolerance of the treatments: respiratory depression: respiratory rate < 10 cycles per minutes (data collected every 5 minutes until to 30 minutes after randomisation and at hospital arrival)

  6. Compare tolerance of the treatments on sedation

    Time frame: at 30 minutes

    Tolerance of the treatments: sedation: Richmond Agitation Sedation Scale (RASS) ≥ 2 or ≤ -2 (data collected every 5 minutes until to 30 minutes after randomisation and at hospital arrival)

  7. Compare tolerance of the treatments on dizziness, pruritus, nausea, vomiting, headache

    Time frame: at 30 minutes

    Tolerance of the treatments: dizziness, pruritus, nausea, vomiting, headache (data collected every 5 minutes until to 30 minutes after randomisation and at hospital arrival)

  8. Compare the impact of the treatments on pain relief

    Time frame: From randomization until the first documented pain divided by two, assessed up to 30 minutes

    Time before achieving pain relief, i.e. time to reach initial pain divided by two (initial VAS / 2)

  9. Compare the impact of the treatments on pain relief

    Time frame: From randomization until the first documented pain relief, assessed up to 30 minutes

    Time before achieving pain relief, i.e. time between randomisation and pain intensity score on VAS ≤ 3

Study contacts

Contact information is provided by the study sponsor or research team.

Frederic ADNET, MD,PHD

CONTACT

[email protected]

01 48 96 44 54 ext. +33

Frederic LAPOSTOLLE, MD,PHD

CONTACT

[email protected]

01 48 96 44 54 ext. +33

Sponsors and collaborators

Lead sponsor

Assistance Publique - Hôpitaux de Paris

Other

Collaborators

  • Medical Developments International Limited

Registry information

Acronym: MAMI

Important dates

Study start
2026
Primary completion
2029
Study completion
2029
First posted
Mar 3, 2026
Registry last updated
Mar 3, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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