Leflunomide Relonchem (Leflunomide)

• Leflunomide is a disease‑modifying antirheumatic drug (DMARD) that interferes with immune cell proliferation, making it effective for chronic inflammatory joint disorders.
• Rheumatoid arthritis: diminishes joint swelling and pain, slows radiographic progression, and improves physical function in adults with moderate to severe disease.
• Psoriatic arthritis: reduces joint inflammation, limits skin lesion exacerbation, and helps maintain mobility in patients with active psoriatic arthritis.
• Early rheumatoid arthritis: contributes to remission rates when used in combination with other disease‑modifying agents, supporting early disease control.

• Leflunomide is converted in vivo to its active metabolite teriflunomide, which selectively inhibits dihydroorotate dehydrogenase, a key enzyme in the de novo synthesis of pyrimidines. By limiting pyrimidine availability, the drug suppresses proliferation of activated T‑lymphocytes and B‑cells, thereby reducing the immune‑mediated inflammatory response characteristic of autoimmune arthritis. The inhibition is reversible and leads to cell‑cycle arrest in the S phase, contributing to the overall immunomodulatory effect without markedly affecting resting lymphocytes.

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

Common Side Effects

• Diarrhea: loose stools or increased frequency.
• Nausea: feeling of sickness or urge to vomit.
• Rash: skin redness or itching.
• Elevated liver enzymes: increased ALT/AST levels.

Serious or Rare Side Effects

• Severe liver injury: hepatitis or hepatic failure requiring monitoring.
• Stevens‑Johnson syndrome: severe skin blistering and mucosal involvement.
• Bone marrow suppression: pancytopenia or anemia.

Before prescribing Leflunomide, clinicians should consider several safety measures.

• Liver function monitoring: check ALT/AST before starting and periodically during therapy.
• Blood pressure monitoring: measure regularly to detect hypertension.
• Pregnancy avoidance: contraindicated in pregnancy; use effective contraception.
• Infection risk assessment: evaluate for active infections before initiating.
• Drug discontinuation before surgery: stop therapy as advised to reduce wound‑healing complications.
• Store at ambient temperature: keep in original packaging, protect from moisture.

Leflunomide interacts with several medicines; some combinations should be avoided while others require close observation.

Major Interactions (Avoid)

• Warfarin: increased anticoagulant effect, may raise INR.
• Methotrexate: additive hepatotoxicity and bone marrow suppression.
• Cholestyramine: reduces leflunomide absorption, decreasing efficacy.

Moderate Interactions (Monitor Closely)

• NSAIDs: may enhance liver enzyme elevations.
• Statins: increased risk of myopathy.
• Oral contraceptives: may reduce contraceptive effectiveness.