Ensifentrine clinical trials
Ensifentrine is named as an intervention in 2 current clinical trials in our USA register. 1 is recruiting patients now. The most common phase is Phase 2. The sponsor with the most trials is Verona Pharma, Inc., a subsidiary of Merck & Co., Inc. (Rahway, New Jersey USA (1). The most-studied condition is Pulmonary Disease, Chronic Obstructive, COPD.
Where Ensifentrine is approved
All regulators →Of the three regulators tracked here, the first to approve Ensifentrine was the US, on 26 Jun 2024.
From the regulators' own registers: FDA Drugs@FDA, the EMA medicines list and Health Canada's Notice of Compliance database. Dates are the first listed approval of a product containing only this substance; combination products and nationally authorised EU medicines are not counted.
Ensifentrine patents and exclusivity
Expiry tracker →Protections still running for marketed products containing Ensifentrine, as listed by the regulators. Expired patents and exclusivities, and discontinued products, are not shown.
- 5 listed patents; the last listed expires 25 Jun 2044 (US 12251384).
- Latest patent on the drug substance itself: 21 Aug 2031 (US 9062047).
- Exclusivity NCE: New chemical entity, until 26 Jun 2029.
Reproduced from the FDA Orange Book and Purple Book (checked 8 Nov 2026) and the European Commission's Union Register of medicinal products (CC BY 4.0; the EU expiry date is calculated exactly as the Commission's register displays it). Listed patents and dates are as submitted to or published by the regulator and may not reflect litigation, invalidation, settlements, lapsed fees or later extensions. This is not legal advice or a freedom-to-operate opinion, and it does not say when a generic or biosimilar will launch.
What health systems spend on Ensifentrine
All medicines →From NHSBSA Prescription Cost Analysis (Open Government Licence v3.0) and CMS State Drug Utilization Data. Both are gross amounts: neither system publishes its discounts or rebates per drug. Products combining several substances are not counted here.
Patient leaflets for Ensifentrine
The package leaflet is the official guide for patients that comes with every medicine. These links go to the regulators that publish it.
- UKUnited Kingdom: Search MHRA ProductsPatient information leaflets and SmPCs for UK-licensed products.
- USUnited States: Search DailyMedFDA-approved labels, including patient and medication guides.
Leaflets differ between brands and countries; always read the one that comes with your own medicine. This is regulatory information, not medical advice.
Trials by status
Trials by phase
Clinical trials of Ensifentrine
2 trials| Study | Phase | Status | Lead sponsor | Registers |
|---|---|---|---|---|
|
Ensifentrine (MK-5884) Study for the Prevention of Chronic Obstructive Pulmonary Disease (COPD) Exacerbations in Adults With a History of Moderate or Severe Exacerbations While Receiving Standard of Care (SOC) (MK-5884-031/RPL554/ENHANCE-3)
NCT07874815 · ClinicalTrials.gov ↗ · Pulmonary Disease, Chronic Obstructive
|
Phase 3 | Recruiting | Merck Sharp & Dohme LLC | USA |
|
Effect of Ensifentrine (MK-5884/RPL554) on Sputum Markers of Inflammation in Chronic Obstructive Pulmonary Disease (COPD) (MK-5884-023/RPL554-CO-207)
NCT05270525 · Pulmonary Disease, Chronic Obstructive, COPD
|
Phase 2 | Active, closed | Verona Pharma, Inc., a subsidiary of Merck & Co., Inc. (Rahway, New Jersey USA | USA |
Registers list studies that are recruiting, about to open, active but closed to enrolment, or enrolling by invitation. The UK and USA registers cover industry-sponsored studies only. Trial titles and statuses are copied from the registry as published.
Conditions studied with Ensifentrine
2 conditionsSponsors
lead sponsor per trial| Lead sponsor | Trials |
|---|---|
| Verona Pharma, Inc., a subsidiary of Merck & Co., Inc. (Rahway, New Jersey USA | 1 |
| Merck Sharp & Dohme LLC | 1 |
By country register
| Register | Trials | Recruiting |
|---|---|---|
| Clinical trials in USA | 2 | 1 |
A trial with sites in more than one country appears in each of those registers.
Questions about Ensifentrine trials
How many clinical trials are testing Ensifentrine?
2 current trials in our USA register name Ensifentrine (also registered as MK-5884) as a drug or biological intervention, as of the registry sync on 8 November 2026. Completed and withdrawn studies are not counted.
Are Ensifentrine trials recruiting patients?
Yes. 1 of the 2 trials is recruiting: 1 with sites in USA. Eligibility and site contacts are on each trial's record. Only the study team can confirm whether a patient is eligible.
Who sponsors Ensifentrine clinical trials?
Verona Pharma, Inc., a subsidiary of Merck & Co., Inc. (Rahway, New Jersey USA (1) and Merck Sharp & Dohme LLC (1). The number in brackets is how many trials each organisation leads.
Where does this information come from?
Every trial, status, phase and sponsor on this page is copied from public ClinicalTrials.gov records by a daily sync. Nothing here describes how Ensifentrine works or whether it is effective, and it is not medical advice.
How this page is built
Everything on this page is copied from public ClinicalTrials.gov registry records — it is not written from memory, and nothing here describes how Ensifentrine works or whether it is effective. Each trial links to its own record so you can check it yourself.
- ClinicalTrials.gov (U.S. National Library of Medicine) ↗ Trial IDs, titles, intervention names and synonyms, phase, overall status, lead sponsor and conditions for every trial on this page
This page is built automatically: a daily sync job reads the registry records behind our country trial registers, collects every trial that lists Ensifentrine (or a registered synonym) as a drug or biological intervention, and tabulates the registry fields directly. Placebos and generic comparators are excluded. There is no AI drafting and no per-compound editorial pass, and the page has not been clinically reviewed. The “last verified” date above is the timestamp of that sync, not a review date. Our general editorial approach is described in our editorial standards and corrections policy. The ClinicalTrials.gov data on this page was last retrieved on 8 Nov 2026. How every register is built: methodology · fixes we have made: corrections log.