Leflunomide

Evidence Level: L5

Predicted Indications: 2

Leflunomide

Pharmacist Assessment Report

Leflunomide: From Rheumatoid Arthritis to Brachydactyly-Syndactyly Syndrome

One-Sentence Summary

Leflunomide is an established drug originally used to treat rheumatoid arthritis and psoriatic arthritis. The TxGNN model predicts it may be effective for brachydactyly-syndactyly syndrome, but there are currently 0 clinical trials and 0 publications supporting this prediction, so it rests on model output alone.

Quick Overview

Item	Content
Original Indication	Rheumatoid arthritis, psoriatic arthritis
Predicted New Indication	Brachydactyly-syndactyly syndrome
TxGNN Prediction Score	0.9993
Evidence Level	L5
Canada Market Status	Marketed (marketed DINs: 18 of 18)
Number of DINs	18 (marketed: 18)
Recommended Decision	Hold

Why is This Prediction Reasonable?

Currently, detailed mechanism of action data is not available in the data compiled for this report. Based on general pharmacological knowledge (not supplied evidence), leflunomide acts through its active metabolite teriflunomide, which inhibits dihydroorotate dehydrogenase (DHODH) and pyrimidine synthesis in rapidly proliferating lymphocytes. This explains its benefit in autoimmune joint disease.

No mechanistic link has been established between this action and the developmental limb pathways involved in brachydactyly-syndactyly syndrome, a congenital malformation disorder. The high TxGNN score is a computational prediction only and is not backed by any trial or publication here.

There is also a safety concern. Leflunomide is known to be teratogenic, which makes its use in a congenital limb-malformation context especially questionable.

A second prediction, colobomatous microphthalmia-rhizomelic dysplasia syndrome (score 0.9993), also has no supporting trials or literature and the same concerns apply.

Clinical Trial Evidence

Currently no related clinical trials registered.

Literature Evidence

Currently no related literature available.

Canada Market Information

Leflunomide is marketed in Canada with 18 valid single-ingredient licences, none cancelled. Dosage form and approved-indication text were not available in the data compiled for this report. Five of the licences are listed below.

DIN	Product Name	Dosage Form	Approved Indication
02241889	ARAVA	Not available	Not available
02241888	ARAVA	Not available	Not available
02256495	APO-LEFLUNOMIDE	Not available	Not available
02261278	TEVA-LEFLUNOMIDE	Not available	Not available
02283972	SANDOZ LEFLUNOMIDE	Not available	Not available

Safety Considerations

Label-based warnings and contraindications were not available in the data compiled for this report. Please refer to the package insert for full safety information.

Contraindication signals from the knowledge graph (not label text): liver failure and liver disease, kidney disease, gallbladder disease, chronic hepatitis B and C virus infection, thrombocytopenia, neutropenia (including congenital forms), agranulocytosis, pancytopenia, anaemia, peripheral neuropathy, interstitial lung disease, pneumocystosis, and aspergillosis.
Drug Interactions: 100 interactions were found, and the 20 shown here are mostly Major. Notable Major interactions include:
- Corticosteroids: hydrocortisone, dexamethasone, betamethasone, budesonide, triamcinolone
- Antidiabetics: pioglitazone and acarbose
- Anti-infectives: clarithromycin and minocycline
- Others: acetylsalicylic acid, bupropion, naltrexone, oxandrolone, oxymetholone, chenodeoxycholic acid
Moderate interactions include metronidazole, chlorpropamide, and acetohexamide. Minor interactions include zinc sulfate and zinc acetate.
Teratogenicity: Leflunomide’s known teratogenicity and long half-life, from enterohepatic recirculation of its active metabolite, are particularly relevant to any congenital or developmental disorder.

Conclusion and Next Steps

Decision: Hold

Rationale: The prediction rests only on a computational score, with no clinical trials, no literature, and no established mechanistic link. Leflunomide’s teratogenicity raises a serious safety concern for a congenital malformation disorder.

To proceed, the following is needed:

Mechanism of action data to assess any biological link to limb-development pathways
Preclinical or literature evidence supporting benefit in brachydactyly-syndactyly syndrome
Package insert warnings and contraindications from Health Canada, and an assessment of teratogenicity risk in the target population
Dosage form and approved-indication details for the Canadian licences
A clear rationale for the target population, since the disease is congenital and the drug is teratogenic
Disclaimer

This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.