Inhaled methoxyflurane for pain during IUD insertion and endometrial biopsy.
A Double-blind Placebo-controlled Randomized Controlled Trial (RCT) of 3ml Methoxyflurane for Intrauterine Device (IUD) Insertion and Endometrial Biopsy
This trial will test whether inhaled methoxyflurane (Penthrox) reduces pain during IUD insertion or endometrial biopsy in adults aged 18–65.
Quick facts
| Phase | Not applicable |
|---|---|
| Study type | Interventional |
| Enrollment | 174 (estimated) |
| Ages | 18 Years to 65 Years |
| Sex | Female |
| Sponsor | Mount Sinai Hospital, Canada Academic / other |
| Locations | 1 site (Toronto, Ontario) |
| Trial ID | NCT07046572 on ClinicalTrials.gov |
What this trial studies
This double-blind, placebo-controlled randomized trial assigns adults undergoing IUD insertion (nulliparous for IUD) or endometrial biopsy to receive either 3 mL inhaled methoxyflurane via a Penthrox inhaler or 3 mL normal saline via an identical placebo inhaler. The primary outcome is patient-reported global pain on a 100 mm visual analogue scale measured 5 minutes after the procedure. Key exclusions include recent opioid or benzodiazepine use, breastfeeding, chronic pain syndromes, renal or liver disease, allergy to methoxyflurane, known susceptibility to malignant hyperthermia, and certain abnormal baseline vital signs. Enrollment takes place at Mount Sinai Hospital/OPG in Toronto and participants must be English-speaking and able to arrange transportation home.
Who should consider this trial
Good fit: Adults 18–65 presenting for IUD insertion (nulliparous for IUD) or endometrial biopsy who are English-speaking, can arrange a ride home, and meet the medical eligibility criteria are ideal candidates.
Not a fit: Patients who are breastfeeding, have chronic pain syndromes, recent opioid/benzodiazepine use, renal or liver disease, allergy or susceptibility to malignant hyperthermia, abnormal baseline vitals, or other exclusion criteria are unlikely to be eligible or benefit.
Why it matters
Potential benefit: If successful, this could provide a rapid, inhaled option to reduce pain and improve comfort during office IUD insertion and endometrial biopsy.
How similar studies have performed: Methoxyflurane (Penthrox) has demonstrated effective short-term analgesia in trauma and emergency settings, but its use specifically during IUD insertion or endometrial biopsy is novel and not well studied.
Eligibility criteria
Show full inclusion / exclusion criteria
Inclusion Criteria * Any participant ≥18 years and ≤ 65 years presenting for an IUD insertion or endometrial biopsy * For IUD insertion, only nulliparous patients * English speaking participants only * Availability of a ride home from the appointment Exclusion Criteria * Use of pain medication that is not an NSAID or acetaminophen (e.g. opioids, benzodiazepines) within past 24 hours * Misoprostol administration within 24 hours * Breastfeeding * Any diagnosed chronic pain syndromes (e.g. fibromyalgia, vaginismus) * Allergy to methoxyflurane * Renal or liver disease * Known or genetically susceptible to malignant hyperthermia or a history of severe adverse reactions in either patient or relatives * Baseline vital signs of systolic blood pressure \<100, diastolic blood pressure \<60 and/or pulse \<60. * Previous unsuccessful office attempt of IUD insertion or endometrial biopsy by the same practitioner (note of clarification: previous unsuccessful IUD insertion or biopsy attempt by a different practitioner will still be eligible) * Clinically evident respiratory impairment
Where this trial is running
Toronto, Ontario
- Opg — Toronto, Ontario, Canada (Recruiting)
How to participate
- Review the eligibility criteria above with your treating physician.
- Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
- Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.