Metaxalone clinical trials
Metaxalone is named as an intervention in 2 current clinical trials in our USA register. 2 are recruiting patients now. All registered phases are Phase 4. The lead sponsor is Primus Pharmaceuticals. The most-studied condition is Sciatica Acute.
Where Metaxalone is approved
All regulators →Of the three regulators tracked here, the first to approve Metaxalone was the US, on 13 Aug 1962.
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.
Metaxalone patents and exclusivity
Expiry tracker →Protections still running for marketed products containing Metaxalone, as listed by the regulators. Expired patents and exclusivities, and discontinued products, are not shown.
- 2 listed patents; the last listed expires 14 May 2043 (US 12485111).
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 Metaxalone
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 Metaxalone
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.
Reference identifiers for Metaxalone
- ChEMBL
- CHEMBL1079604
- DrugBank
- DB00660
- PubChem CID
- 15459
- CAS number
- 1665-48-1
- FDA UNII
- 1NMA9J598Y
- Wikidata
- Q6823309
- Wikipedia
- Metaxalone
Codes that identify this medicine in other databases, from Wikidata (CC0), matched by its ChEMBL ID. The ATC code is the WHO classification of what the medicine is used for.
Trials by status
Trials by phase
Clinical trials of Metaxalone
2 trials| Study | Phase | Status | Lead sponsor | Registers |
|---|---|---|---|---|
|
Efficacy of M640 in Acute Lumbosacral Musculoskeletal Conditions.
NCT06157177 · Sciatica Acute, Lumbar Spinal Stenosis
|
Phase 4 | Recruiting | Primus Pharmaceuticals | USA |
|
Testing Healthy Participants for Drowsiness After Single Dosing of Two Different Doses of Muscle Relaxer
NCT07801066 · Healthy Participants
|
Phase 4 | Recruiting | Primus Pharmaceuticals | 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 Metaxalone
3 conditionsSponsors
lead sponsor per trial| Lead sponsor | Trials |
|---|---|
| Primus Pharmaceuticals | 2 |
By country register
| Register | Trials | Recruiting |
|---|---|---|
| Clinical trials in USA | 2 | 2 |
A trial with sites in more than one country appears in each of those registers.
Questions about Metaxalone trials
How many clinical trials are testing Metaxalone?
2 current trials in our USA register name Metaxalone (also registered as M640) as a drug or biological intervention, as of the registry sync on 10 November 2026. Completed and withdrawn studies are not counted.
Are Metaxalone trials recruiting patients?
Yes. 2 of the 2 trials are recruiting: 2 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 Metaxalone clinical trials?
The lead sponsor is Primus Pharmaceuticals. 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 Metaxalone 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 Metaxalone 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 Metaxalone (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 10 Nov 2026. How every register is built: methodology · fixes we have made: corrections log.