A Phase 3 interventional study of Analgesic management with Methoxyflurane as first-line treatment and Pain treatment according to the usual analgesic management protocol of the emergency department of the participating center. in Pain Management, sponsored by University Hospital, Tours. Not yet recruiting at 3 sites in France. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-08-03.
Sponsored by University Hospital, Tours · Phase 3, Interventional, and Treatment
Pain is one of the most frequent patient-reported symptoms in emergency departments (EDs). Pain management could be very challenging, notably for patients that must wait in an ED waiting room. In such context, antalgic drugs that could be used are mainly oral medications with the paracetamol (acetaminophen), the non-steroidal anti-inflammatory drugs and the weak and strong opioid drugs as the main available options, depending on the degree of pain. Those commonly used painkillers, with oral administration, need a delay (approximatively 20 to 30 minutes) before the full analgesic effect could be observed. Methoxyflurane is a self-administered inhaled analgesic used for over 40 years in countries such as Australia. Methoxyflurane has a rapid onset of action, is well tolerated and is widely used for moderate to severe traumatic pain, with several trials that have investigated it efficacy in such indication. However, no data are available concerning the management of non-traumatic painful diseases. Thus, the aim of the open-label, multicenter, and two parallel-arms superiority PAIN-THROX randomized controlled trial is to assess how using self-administered inhaled Methoxyflurane could reduce the time to pain relief comparatively with oral analgesic medications for patients seeking in an ED for non-traumatic painful diseases and who could wait in an ED waiting room.
Patients seeking in an ED for a non-traumatic painful disease and with a condition allowing staying in waiting room will be randomly allocated in a 1:1 ratio between Methoxyflurane (intervention group) or oral standard analgesic medications according to the degree of pain and based on the ED pain-management protocol.
Primary outcome will be the time to pain relief within the 30 minutes after randomization. Pain will be measured using the visual analogue scale. Secondary outcomes will be the time to pain relief within 3 subgroups according to the degree of pain at time to randomization (moderate, strong and intolerable), the evolution of the pain between 30 min and 2 hours post randomization, the need for rescue analgesic therapies and the occurrence adverse events.
Exclusion Criteria:
Age \< 18 years
Hypersensitivity to the active substance or to any other fluorinated anesthetic or to any excipient.
analgesic management with Methoxyflurane as first-line treatment
Drug: Analgesic management with Methoxyflurane as first-line treatment
Pain treatment according to the usual analgesic management protocol of the emergency department of the participating center.
Drug: Pain treatment according to the usual analgesic management protocol of the emergency department of the participating center.
The investigational medicinal product is methoxyflurane, presented as a liquid for vapor inhalation, supplied in 3 mL vials and marketed under the name Penthrox®. Each vial contains 3 mL of methoxyflurane at 99.9%, and includes butylated hydroxytoluene (E321) as an excipient with known effect (0.01% w/w). Each pack contains one methoxyflurane vial, an inhaler, and an activated carbon chamber. Methoxyflurane is self-administered under the supervision of a trained healthcare professional, either a physician or a nurse. Administration is performed using the provided handheld inhaler.
Administration of oral analgesic treatment in the emergency reception area according to the protocol in force in the emergency department.
Time to Pain Reduction of at Least 30 mm on the Visual Analog Scale (VAS)
Time from randomization to the first decrease of at least 30 mm from baseline pain score measured on a 100-mm Visual Analog Scale (VAS), assessed within the 30 minutes after randomization. The VAS is a simple pain measurement tool consisting of placing a mark on a colored ruler graduated in millimeters, thereby associating a numerical value ranging from 0 (no pain) to 100 millimeters (unbearable pain).
Time frame: At Inclusion An at 3, 5, 10, 15, 20, 25, and 30-minutes post randomisation
Evaluate the effect of methoxyflurane based on pain intensity
Assess the effect of methoxyflurane in each of the three subgroups defined by pain intensity and categorized as "moderate" pain (VAS between 40 and 59), "severe" pain (VAS between 60 and 79 mm), and "unbearable" pain (VAS ≥ 80 mm) at enrollment
Time frame: from baseline to 30 minutes after randomization
Compare the prolonged analgesic effect (ranging from 30 minutes to 2 hours) of methoxyflurane
Compare the prolonged analgesic effect of methoxyflurane with that of "standard"pain management with the measurement of Pain Intensity (VAS) at 60, 90, and 120 Minutes Post-Randomization
Time frame: At 60 minutes after randomization, 90 minutes and 120 minutes
Use of Rescue Analgesic Treatment After 30 Minutes Post-Randomization
Participants requiring any analgesic treatment due to insufficient pain relief or recurrence of pain more than 30 minutes after randomization.
Time frame: More than 30 minutes after randomization
Class of Rescue Analgesic Treatment Used After 30 Minutes Post-Randomization
Therapeutic class of the analgesic treatment administered for insufficient pain relief or recurrence of pain more than 30 minutes after randomization.
Time frame: More than 30 minutes after randomization
Adverse Events and Serious Adverse Events
Number of participants experiencing adverse events (AEs) and serious adverse events (SAEs) during the study period.
Time frame: From baseline to 24 hours
This study is not yet recruiting, as verified in Jul 2026. You cannot join it, but the record below documents what was studied.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
University Hospital, Tours