Skip to content
Clinical Trials – home

Rare diseases

Investigational molecules

Locations

Our offerNewsroom

Not yet recruiting

Methoxyflurane versus oral oxycodone hydrochloride and morphine sulfate for pain relief in sickle cell disease vaso‑occlusive crises

Verified siteRegistered drugNo placebo
Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

What is this trial about?

A plain-language summary of the goals, design and what participants do

The study involves people with sickle cell disease who experience a painful episode called a vaso-occlusive crisis. The investigation compares a fast‑acting inhaled pain medicine, methoxyflurane, with standard oral opioid pills such as morphine sulfate or oxycodone hydrochloride. The purpose is to see which approach provides quicker and more effective relief of pain when patients first arrive at the emergency department.

When a participant comes to the emergency department with a crisis, they receive either the inhaled medication or an oral opioid pill. Their pain level is recorded every ten minutes for the first hour using a line‑marking tool called the Visual Analog Scale. After one hour, the patient rates their overall satisfaction on a numbered rating system known as the Likert scale, and the attending nurse also records a satisfaction rating. Throughout the stay, the amount of any additional pain medicines given, the length of the hospital visit, and basic safety checks are noted, after which the patient is discharged.

The research process

The trial runs in 8 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Baseline assessment and randomization

    After joining the study, a brief assessment records age, gender, sickle cell disease status, and current pain level.

    Based on the assessment, the patient is randomly assigned to receive either methoxyflurane inhalation or an oral opioid (morphine sulfate 20 mg or oxycodone hydrochloride 10 mg).

  2. Step 2

    Administration of the assigned medication

    If assigned to the test arm, the patient uses a small inhaler that delivers 6 ml of methoxyflurane by inhalation; the dose is given once at the start of the emergency department visit.

    If assigned to the comparator arm, the patient takes a single oral tablet of either morphine sulfate 20 mg or oxycodone hydrochloride 10 mg immediately after randomization.

  3. Step 3

    Pain monitoring during the first hour

    A nurse records the pain intensity using a visual analog scale (a line marked from 0 = no pain to 100 = worst pain) every 10 minutes for the first 60 minutes after medication administration.

  4. Step 4

    Patient satisfaction rating

    At the 60‑minute mark, the patient rates overall satisfaction with the pain relief on a likert scale ranging from 1 (very dissatisfied) to 10 (very satisfied).

  5. Step 5

    Additional analgesic treatment if needed

    If pain remains high, the medical team may give intravenous morphine and may also provide other analgesics such as nefopam, paracetamol, or tramadol.

    These additional medications are given until the patient is discharged from the emergency department.

  6. Step 6

    Hospital stay and discharge

    The total length of stay, from arrival in the emergency department to discharge from the hospital, is recorded in days.

    The number of bottles of methoxyflurane or the number of oral opioid tablets used is documented for cost analysis.

  7. Step 7

    Follow‑up laboratory tests

    Blood tests to evaluate kidney and liver function are performed between the third and seventh day of hospitalization; the worst result from any test in this period is used for safety assessment.

  8. Step 8

    Monitoring for complications

    During the hospital stay, the patient is observed for possible acute chest syndrome, stroke, or other neurologic events, and any occurrence is recorded.

Who can join the trial?

8 criteria

  • Must have sickle cell disease (a blood disorder) with one of the following genetic types: SS, Sbeta0, SC, or Sbéta+.
  • Must be older than 18 years.
  • Must be at the emergency department because of a vaso‑occlusive crisis (a painful blockage of blood flow) and rate the pain higher than 6 out of 10 on a Visual Analog Scale (a line where 0 means no pain and 10 means the worst pain).
  • Must need pain relief with intravenous morphine (pain medicine given through a vein).
  • If you are a woman who could become pregnant, you must use effective contraception (birth control).
  • Must have a French social security (health coverage) affiliation.
  • Must give informed consent (agree to join after understanding the study) or, if the pain is very severe, give an oral agreement first and sign a deferred written consent later.
  • Must be able to speak and understand French.

Who cannot join the trial?

13 criteria

  • Refusal to participate – if you do not agree to be in the study.
  • Clinically evident respiratory depression – significant slowing of breathing that doctors can see.
  • Suspected acute chest syndrome at admission: chest pain and oxygen saturation under 95% – low oxygen levels measured with a finger clip.
  • Failure of vital functions requiring stay in the intensive care unit – if your organs are failing and you need treatment in a special hospital unit for very sick patients.
  • Contraindication for oral use of opioid analgesics such as oral oxycodone or morphine – if you cannot safely take strong pain medicines by mouth.
  • Previous inclusion in the MOOD study – if you have already taken part in this research before.
  • Pregnant woman – if you are pregnant.
  • Breast feeding – if you are currently nursing a baby.
  • Patient under guardianship, administrative tutorship, deprived of liberty, or unable to give informed consent – if a legal guardian makes decisions for you, you are in prison, or you cannot give permission yourself.
  • Inability to use Penthrox® or take oral opioids because you cannot understand or follow the instructions (due to cognitive impairment, altered consciousness, or physical limitations) – if you are confused, very sleepy, or have physical problems that prevent self‑administration.
  • Contraindication for Methoxyflurane (Penthrox®) – if you have a medical reason that makes the inhaled drug unsafe for you.
  • Altered level of consciousness or excessive sleepiness – if you are unusually drowsy or not fully awake.
  • Clinically evident cardiovascular instability – if your heart and blood pressure are unstable as seen by doctors.
Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

Tell us about your condition – we search every trial in Europe and connect you with the right site.

We usually reply within a few days

Verified sites

All sites with verified contact details – recruitment status may not be available; ask directly

Trial locations

Where you can join this trial

Countries are shaded by recruitment status. Click a recruiting country to ask about joining there.

Not yet recruiting
Not finding your country?

Not sure what to do next?

Joining a clinical trial can seem overwhelming. We guide you step by step, so you know exactly what to expect and how we support you through the process.

See the full process and FAQ

Investigated drugs

  • Morphine sulfate

    is a strong pain‑relieving medicine that is taken by mouth. In this study it is used as a standard treatment to see how quickly it can reduce the severe pain that people with sickle cell disease feel during a vaso‑occlusive crisis. Researchers compare its speed and effectiveness with the inhaled medicine being tested.

  • Oxycodone hydrochloride

    is another powerful oral opioid painkiller. It is given to patients in the emergency department as a usual way to control the intense pain of a sickle cell crisis. The trial looks at how its pain‑relief timing and overall benefit compare with the inhaled medication.

  • Methoxyflurane

    is a liquid that is breathed in as a vapor. Participants inhale it through a small device, allowing the medicine to act quickly through the lungs. In this trial it is being tested as a fast‑acting option for pain relief in sickle cell vaso‑occlusive crises, and its speed and effectiveness are measured against the oral opioids.

What is already known about the treatment

  • Morphine Sulfate

    This medication is taken by mouth as a tablet, usually 20 mg per dose. It is an established, approved opioid that has been used for many years and is well described in medical literature. Morphine is given to relieve moderate to severe pain, such as the pain from a sickle cell crisis. It works by attaching to mu‑opioid receptors in the brain and spinal cord, which lowers the feeling of pain, and it belongs to the class of opioid analgesics.

  • Methoxyflurane

    The drug is supplied as a liquid that is inhaled as a vapor, typically 6 ml given through a special inhaler. It is approved in several countries for short‑term pain relief and has a growing body of research supporting its use in emergency settings. Methoxyflurane is used to quickly ease acute pain, for example during a vaso‑occlusive crisis in sickle cell disease. It produces analgesia by depressing nerve activity in the brain, likely through effects on GABA and NMDA pathways, and it is classified as an inhaled volatile anesthetic analgesic.

  • Oxycodone Hydrochloride

    This drug is taken orally, often as a 10 mg tablet. It is a widely approved opioid with extensive documentation in the medical literature. Oxycodone is prescribed for moderate to severe pain, including the intense pain of sickle cell crises. It relieves pain by stimulating mu‑opioid receptors in the central nervous system, reducing pain signals, and it belongs to the opioid analgesic class.

Investigated diseases

Sickle cell disease - A hereditary blood disorder that causes red blood cells to become stiff and shaped like a crescent. These abnormal cells can block small blood vessels, leading to episodes of pain that come and go. Over time, the blocked flow can cause fatigue and reduced oxygen delivery to tissues. Repeated blockages may lead to gradual damage in bones, joints, and organs. The condition often results in chronic anemia, which can make individuals feel tired more often. Symptoms typically worsen during infections, dehydration, or high stress.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-518043-38-00Protocol codeAPHP180608Estimated enrolment198 patientsSponsorAssistance Publique Hopitaux De Paris

sourced from the EU Clinical Trials Register and site verification

Want to learn more about this trial or check if you can participate?

Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

Tell us about your condition – we search every trial in Europe and connect you with the right site.