DR Medhat MRCP

Leflunomide :
• Mechanism of action :
-- Mitochondrial dihydro-orate dehydrogenase → - -pyrimidine synthesis → -- expantion
of autoimmune lymphocytes→ ↓ pain & swelling in rheumatoid arthritis.
• Side effects :
1) Serious hepatotoxicity (↑ALT &/or AST ≤ 2 folds of upper normal in 15-20% of
cases)
2) B.M depression (pancytopenia).
3) Allergy /itching →↓ dose ± antihistaminics , if severe → stop & washout.
4) Hair loss , headache , GIT upset →↓ doses , if severe → stop & washout.
5) Hypertension >140/90 → treat HTN → if still HTN → stop & washout.
6) Weight loss > 10% → if no other cause→↓ doses→ still wt loss→ stop & washout.
7) Pneumonitis/SOB → stop & washout.
Monitoring of leflunomide : → ALT/AST/CBC monthly for 6 months
If stable → check 2 monthly thereafter.
If ALT/AST ↑ but ≤ 2 folds of upper normal→↓dose & recheck in 1 week
If CBC↓↓ (i.e WBCs