Trial results
AI generated results summary. Written by an AI model from the official source data and checked on a sample basis. It can contain mistakes, so confirm anything important against the original source. How we use AI
According to the results reported on ClinicalTrials.gov, this trial (NCT03654326) enrolled 187 participants — 94 in the gefapixant group and 93 in the placebo group (a placebo is a dummy treatment with no active ingredient, used for comparison). The trial was measuring changes in daily pelvic pain scores in people with endometriosis-related pelvic pain, using a scale of 0 to 10 where 0 meant no pain and 10 meant extremely severe pain. It also tracked how many participants experienced an unwanted medical event (called an adverse event) during the study, and how many stopped taking the study drug because of one. Most participants completed the study — 88 in the gefapixant group and 87 in the placebo group. The reported data shows that, for the main pain measure (average daily pelvic pain combining period-related and non-period-related pain, assessed roughly between weeks 4 and 8), scores in the gefapixant group decreased by an average of 2.2 points from their starting level, while scores in the placebo group decreased by an average of 1.7 points. For period-related pain alone, the reported decreases were 2.0 points (gefapixant) and 1.3 points (placebo). For pain not related to periods, the reported decreases were 2.3 points (gefapixant) and 1.8 points (placebo). In all cases, both groups showed a decrease from their starting scores. The reported data also shows that 53.2% of participants in the gefapixant group and 35.5% in the placebo group experienced at least one adverse event during the study period. Additionally, 3.2% of those in the gefapixant group stopped taking the study drug because of an adverse event, compared with 0.0% in the placebo group. These are the results as reported to ClinicalTrials.gov. They are not medical advice — always discuss what they mean for you with your doctor.
View full results on ClinicalTrials.gov ↗ · Read the linked publication on PubMed (PMID 39260540) ↗
These are the results as reported to ClinicalTrials.gov, not medical advice. Verify independently with the trial site and discuss what they mean for you with your doctor.
Phase 2 Endometriosis Trial, Completed
Who may be able to join
AI generated eligibility summary. Written by an AI model from the official source data and checked on a sample basis. It can contain mistakes, so confirm anything important against the original source. How we use AI
Who might be able to join this trial:
- You have been diagnosed with endometriosis through surgery (either keyhole surgery or open abdominal surgery).
- You experience both period-related AND non-period-related pelvic pain that is moderate to severe (rated 5 or higher on a scale of 0–10).
- You have been having natural, regular menstrual cycles before your first visit.
- Your body mass index (BMI) falls between 18 and 40 at the time of your first visit.
- You are not pregnant, not breastfeeding, and are willing to follow the trial's contraception guidelines.
- You are willing to switch from your usual pain medication to only the pain relief options allowed within the study.
Who may not be able to join:
- You have had your uterus removed (hysterectomy) and/or both ovaries removed (bilateral oophorectomy).
- You have unexplained vaginal bleeding that has not been diagnosed.
- You have long-term pain in other parts of the body (not the pelvis) that is unrelated to endometriosis and requires ongoing pain medication.
- You have a significant gynaecological condition found during the screening process (confirm with trial site).
- You have a history of a severe allergic reaction or serious skin reaction to sulfonamide antibiotics or other medicines containing sulfonamide.
- You have a known allergy, sensitivity, or reason you cannot take the study drug gefapixant or any of its ingredients.
- You have an allergy or intolerance to naproxen sodium (the rescue pain medication used in the trial), or you have previously had asthma, hives, or allergic reactions after taking aspirin or other anti-inflammatory pain medicines (such as ibuprofen).
- Your endometriosis pain has previously not responded to certain hormone-based treatments, such as the combined contraceptive pill, or other hormonal therapies used for endometriosis (confirm with trial site).
- You have a positive pregnancy test at any point before being enrolled in the trial.
- You have needed to use opioid/narcotic pain medicines continuously for more than 2 weeks to manage your endometriosis pain within the last 6 months.
Important: Always verify eligibility with the trial site directly before applying.
Based on publicly available eligibility criteria from ClinicalTrials.gov. Verify directly with the trial site before acting. This is not medical advice.
Contact this trial
Principal Investigator: Medical Director, Merck Sharp & Dohme LLC
Australian sites
Contact details sourced from ClinicalTrials.gov. Verify directly with the trial site before attending.
GP referral letter
Print a one-page summary to share with your doctor.
Trial details
Where this trial is recruiting
5 site(s) in Australia. Confirm current status and contact details directly with the trial site.
Primary endpoints
Change From Baseline in Average Daily Pelvic Pain Score During Treatment Cycle 2; Percentage of Participants Who Experienced an Adverse Event; Percentage of Participants Who Discontinued Study Drug Due to an Adverse Event
Can't join this trial?
Data last synced from ClinicalTrials.gov: 28 July 2026. Trial status can change. Always verify current status directly with the trial site before making any decision.