Leflunomide Morningside Healthcare (Leflunomide)

Leflunomide is a disease-modifying antirheumatic drug that targets autoimmune joint disorders.

• Rheumatoid arthritis: reduces joint inflammation and slows structural damage.
• Psoriatic arthritis: alleviates skin and joint symptoms by modulating immune activity.
• Juvenile idiopathic arthritis: helps control disease activity in pediatric patients, improving function and quality of life.

• Leflunomide inhibits the mitochondrial enzyme dihydroorotate dehydrogenase, which is essential for de novo pyrimidine synthesis. By limiting pyrimidine availability, the drug suppresses proliferation of activated lymphocytes, thereby reducing the autoimmune response that drives joint inflammation and damage.

Leflunomide may cause a range of adverse reactions, from mild to severe.

Common Side Effects

• Diarrhea: mild to moderate gastrointestinal upset.
• Elevated liver enzymes: transient increase in ALT/AST.
• Hypertension: new‑onset or worsening blood pressure.
• Rash: non‑specific skin eruptions.
• Nausea: occasional feeling of queasiness.
• Headache: mild to moderate intensity.

Serious or Rare Side Effects

• Severe liver injury: jaundice, hepatic failure.
• Bone marrow suppression: anemia, leukopenia, thrombocytopenia.
• Pulmonary toxicity: interstitial lung disease or pneumonitis.
• Severe cutaneous reactions: Stevens‑Johnson syndrome, toxic epidermal necrolysis.

Before initiating therapy, clinicians should assess baseline health status and monitor regularly.

• Liver function: obtain baseline ALT/AST and repeat periodically.
• Blood counts: monitor complete blood count for signs of cytopenia.
• Blood pressure: check regularly, especially in patients with hypertension history.
• Pregnancy: contraindicated; ensure effective contraception for women of childbearing potential.
• Infections: assess for active infections and avoid initiating during severe infection.
• Store at ambient temperature: keep below 25 °C in the original container, protect from moisture and direct sunlight.

Leflunomide can alter the pharmacokinetics of several concomitant medicines.

Major Interactions (Avoid)

• Warfarin: increased anticoagulant effect, risk of bleeding.
• Methotrexate: additive hepatotoxicity, monitor liver enzymes closely.

Moderate Interactions (Monitor Closely)

• Rifampin: reduces leflunomide plasma levels, may diminish efficacy.
• Cholesterol‑lowering agents (e.g., statins): increased risk of myopathy.
• Live vaccines: may diminish vaccine efficacy and increase infection risk.