Leflunomide Viatris (Leflunomide)

• Leflunomide is a disease‑modifying antirheumatic drug that targets immune‑mediated inflammatory pathways in several arthritic conditions.
• Rheumatoid arthritis: reduces joint inflammation, pain, and structural damage, improving functional ability and quality of life.
• Psoriatic arthritis: diminishes skin and joint symptoms, slowing disease progression and decreasing the need for additional systemic therapies.
• Other autoimmune inflammatory conditions: modulates immune response to control disease activity and limit organ damage.
• Adult patients with moderate to severe disease: provides an oral treatment alternative when biologic therapy is unsuitable or as part of combination regimens.

• Leflunomide inhibits the mitochondrial enzyme dihydroorotate dehydrogenase, which blocks de novo pyrimidine synthesis. This reduction limits the proliferation of activated T‑lymphocytes and B‑lymphocytes, thereby dampening the immune response that drives inflammation in autoimmune diseases.

Leflunomide may cause a range of adverse reactions, which are categorized by frequency and severity.

Common Side Effects

• Diarrhea: loose stools or increased bowel movements.
• Nausea: feeling of sickness or urge to vomit.
• Alopecia: thinning or loss of hair.
• Elevated liver enzymes: increased ALT/AST levels indicating hepatic stress.

Serious or Rare Side Effects

• Severe liver injury: jaundice or hepatic failure requiring close monitoring.
• Stevens‑Johnson syndrome or toxic epidermal necrolysis: severe skin reactions that may be life‑threatening.
• Bone marrow suppression: anemia, leukopenia, or thrombocytopenia affecting blood cell production.

When prescribing Leflunomide, clinicians should observe several precautionary measures to minimize risks.

• Liver function monitoring: check ALT/AST before starting and periodically during therapy.
• Blood pressure assessment: monitor for hypertension, especially in patients with cardiovascular risk.
• Hematologic surveillance: perform complete blood counts regularly to detect bone marrow effects.
• Pregnancy contraindication: avoid use in women of childbearing potential; ensure effective contraception.
• Hepatic impairment avoidance: do not initiate in patients with severe liver disease.
• Renal function consideration: adjust use in moderate renal impairment with caution.
• Store at ambient temperature: keep tablets in original packaging, protect from moisture and heat.

Leflunomide can interact with other medicines, affecting its efficacy or safety profile.

Major Interactions (Avoid)

• Warfarin: increased anticoagulant effect leading to bleeding risk.
• Live vaccines: heightened risk of infection due to immunosuppression.
• Cholesterol‑binding resins (e.g., cholestyramine): reduce Leflunomide absorption, decreasing effectiveness.

Moderate Interactions (Monitor Closely)

• Statins: potential for increased myopathy risk.
• Oral contraceptives: reduced hormonal efficacy, consider alternative contraception.