Leflunomide Sandoz Ltd (Leflunomide)

Leflunomide is a disease‑modifying antirheumatic drug that acts on inflammatory pathways in autoimmune arthritis.

• Rheumatoid arthritis: reduces disease activity and slows joint damage.
• Psoriatic arthritis: improves skin and joint symptoms while inhibiting disease progression.
• Inadequate response to other DMARDs: provides an alternative therapeutic option for patients who have not responded sufficiently to first‑line treatments.

• 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 inflammatory response that drives joint damage in rheumatoid and psoriatic arthritis.

Leflunomide may cause a range of adverse reactions.

Common Side Effects

• Diarrhoea: mild to moderate gastrointestinal upset.
• Nausea and vomiting: transient, often improves with food.
• Alopecia: reversible hair thinning.
• Rash: non‑specific skin eruptions.
• Headache: occasional, usually mild.
• Hypertension: new‑onset or worsening blood pressure.

Serious or Rare Side Effects

• Hepatotoxicity: elevated liver enzymes or severe liver injury.
• Severe infections: opportunistic or bacterial infections requiring medical attention.
• Stevens‑Johnson syndrome/toxic epidermal necrolysis: life‑threatening skin reactions.
• Bone‑marrow suppression: pancytopenia or severe neutropenia.
• Interstitial lung disease: respiratory symptoms with imaging changes.
• Severe hypertension or hypertensive crisis.

Before initiating therapy, clinicians should evaluate baseline organ function and counsel patients on risk mitigation.

• Liver monitoring: obtain baseline liver function tests and repeat periodically.
• Blood pressure: measure regularly and manage hypertension as needed.
• Hematology: monitor complete blood count for signs of bone‑marrow suppression.
• Hepatic impairment: avoid use in patients with severe liver disease.
• Pregnancy: contraindicated; ensure effective contraception throughout treatment and for several months after discontinuation.
• Store at ambient temperature: keep in the original container, protect from moisture and direct sunlight.

Leflunomide can interact with several medicines, requiring careful management.

Major Interactions (Avoid)

• Warfarin: increased anticoagulant effect and risk of bleeding.
• Statins (e.g., simvastatin): heightened risk of hepatotoxicity.
• Azathioprine or other myelosuppressants: additive bone‑marrow suppression.

Moderate Interactions (Monitor Closely)

• Methotrexate: combined hepatotoxic potential; monitor liver enzymes.
• Antihypertensive agents: possible reduction in blood‑pressure control.
• Oral contraceptives: decreased efficacy, consider alternative contraception.