Mefenamic Acid
| Evidence Level: L2 | Predicted Indications: 8 |
Table of Contents
Mefenamic Acid: From Pain Relief (NSAID) to Rheumatoid Arthritis
One-Sentence Summary
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) marketed in the US as oral capsules. The registry data carry no indication text; its standard use is analgesia. The TxGNN model predicts it may be effective for rheumatoid arthritis, supported by 0 registered clinical trials and 20 publications. These are mostly 1966-1979 studies showing symptomatic benefit comparable to other NSAIDs.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Not stated in the registry data (general knowledge: mild-to-moderate pain) |
| Predicted New Indication | Rheumatoid arthritis |
| TxGNN Prediction Score | 99.73% |
| Evidence Level | L2 |
| US Market Status | ✓ Marketed |
| Number of NDAs | 6 licenses (all ANDA generics, 3 distinct application numbers) |
| Recommended Decision | Hold |
Why is This Prediction Reasonable?
Detailed mechanism of action data is not available in the source record. Mefenamic acid is an NSAID that inhibits COX-1/COX-2 and thereby prostaglandin synthesis. This plausibly reduces the pain and swelling of inflammatory joint disease.
Rheumatoid arthritis is an inflammatory condition in which prostaglandin-mediated pain and stiffness are major symptoms. Several 1966-1979 clinical studies, including a double-blind crossover trial and comparisons with ibuprofen, report symptomatic benefit. Mefenamic acid performed comparably to ibuprofen in these studies.
Two limits apply. First, it is not disease-modifying and offers no clear advantage over established NSAIDs. Second, the NSAID class risks (GI, renal, cardiovascular) apply.
Clinical Trial Evidence
Currently no related clinical trials registered.
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 373989 | 1979 | RCT | Curr Med Res Opin | Double-blind crossover in 24 patients; mefenamic acid, flurbiprofen and sulindac were all significantly better than placebo on pain, joint tenderness and morning stiffness |
| 330287 | 1977 | Comparative trial | J Int Med Res | Randomized double-blind study in 40 patients; analgesic and anti-inflammatory effect not significantly different from ibuprofen |
| 796645 | 1976 | Comparative trial | Med J Aust | Double-blind crossover vs ibuprofen; mefenamic acid compared favourably, with mild, mostly gastrointestinal side effects |
| 4294443 | 1967 | Clinical study | Ann Rheum Dis | Early clinical study of mefenamic acid in rheumatoid arthritis (no abstract available) |
| 5920657 | 1966 | Comparative study | Br Med J | Compared mefenamic and flufenamic acid with aspirin and phenylbutazone (no abstract available) |
| 6039589 | 1967 | Comparative study | Ann Rheum Dis | Outpatient assessment methods and comparison of fenamates with phenylbutazone and aspirin (no abstract available) |
| 10439 | 1976 | Clinical study | J Rheumatol | Single-blind evaluation of 10 antirheumatic drugs in 684 patients, using subjective pain indices |
| 4890710 | 1967 | Clinical study | Reumatismo | Preliminary double-blind observations of mefenamic acid in rheumatoid arthritis (no abstract available) |
| 306128 | 1978 | Review | Scott Med J | Review of the place of mefenamic acid in rheumatoid arthritis treatment |
| 29548675 | 2018 | Case-crossover study | Am J Cardiol | Stroke and myocardial infarction risk with NSAIDs in 5,921 rheumatoid arthritis patients (a class-level safety signal) |
US Market Information
| Authorization Number | Product Name | Dosage Form | Approved Indication |
|---|---|---|---|
| ANDA090562 | Mefenamic acid (Micro Labs Limited) | Capsule | Not listed in registry data |
| ANDA090562 | Mefenamic acid (Bryant Ranch Prepack) | Capsule | Not listed in registry data |
| ANDA091322 | Mefenamic Acid (Advanced Rx of Tennessee) | Capsule | Not listed in registry data |
| ANDA091322 | Mefenamic Acid (Lupin Pharmaceuticals) | Capsule | Not listed in registry data |
| ANDA091608 | Mefenamic Acid (Misemer Pharmaceuticals) | Capsule | Not listed in registry data |
Safety Considerations
Please refer to the package insert for safety information. No structured warnings, contraindications or drug interaction data were retrieved.
Safety signals from the retrieved literature:
- Class risk: NSAIDs carry GI, renal and cardiovascular risks, including stroke and myocardial infarction risk in rheumatoid arthritis patients (PMID 29548675).
- Autoimmune haemolytic anaemia: three cases were reported with mefenamic acid therapy (PMID 5676955, 1968).
- Enteropathy: severe enteropathy with villous atrophy has been described in prolonged users (PMID 29095288).
Conclusion and Next Steps
Decision: Hold
Rationale: The evidence is limited to small, decades-old studies showing symptom relief no better than established NSAIDs. There are no registered trials, and mefenamic acid is not disease-modifying. Package insert safety data has not yet been reviewed.
To proceed, the following is needed:
- Package insert warnings and contraindications (a blocking gap for safety screening)
- Mechanism of action data from DrugBank
- Verification of the design and phase of the historical studies, and any modern controlled data
- A comparative rationale versus current NSAIDs, given the class GI, renal and cardiovascular risks
This report is for research reference only and does not constitute medical advice. Repurposing candidates require clinical validation before use.
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.