Leflunomide Medac (Leflunomide)

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

• Rheumatoid arthritis: reduces joint inflammation, pain, and structural damage.
• Psoriatic arthritis: improves skin lesions and joint symptoms.
• Moderate to severe active disease refractory to other DMARDs: provides an alternative therapeutic option when first‑line agents are insufficient.

• Leflunomide inhibits dihydroorotate dehydrogenase, a key enzyme in de novo pyrimidine synthesis. By blocking this pathway, it limits the proliferation of activated lymphocytes, thereby reducing the autoimmune response that drives joint inflammation and tissue damage in rheumatoid and psoriatic arthritis.

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

Common Side Effects

• Diarrhea: mild to moderate gastrointestinal upset.
• Nausea: occasional feeling of queasiness.
• Alopecia: reversible hair thinning.
• Rash: skin irritation or erythema.
• Elevated liver enzymes: mild hepatic transaminase rise.
• Hypertension: increase in blood pressure readings.

Serious or Rare Side Effects

• Severe liver injury: potential hepatic failure requiring monitoring.
• Stevens‑Johnson syndrome: rare, life‑threatening skin reaction.
• Bone marrow suppression: pancytopenia or severe neutropenia.
• Pulmonary toxicity: interstitial lung disease.
• Severe infections: opportunistic infections due to immunosuppression.
• Teratogenicity: fetal harm if exposure occurs during pregnancy.

Before initiating therapy, clinicians should assess patient suitability and monitor key parameters.

• Pregnancy contraindication: avoid use in pregnant women and those planning conception.
• Liver function monitoring: perform baseline and periodic liver enzyme tests.
• Blood pressure monitoring: check regularly, especially in hypertensive patients.
• Hematologic monitoring: periodic complete blood counts to detect cytopenias.
• Renal impairment caution: adjust use in severe renal dysfunction.
• Store at below 25°C: keep in the original pack, protect from moisture.

Leflunomide can interact with several medicines, altering efficacy or safety.

Major Interactions (Avoid)

• Methotrexate: combined hepatotoxicity risk.
• Warfarin: increased anticoagulant effect.
• Live vaccines: reduced vaccine efficacy and potential infection.
• Carbamazepine and other enzyme‑inducing anticonvulsants: lower leflofuno­mid exposure.
• TNF‑α inhibitors: heightened immunosuppression.

Moderate Interactions (Monitor Closely)

• NSAIDs: additive liver toxicity.
• Statins: increased risk of myopathy.
• ACE inhibitors: possible aggravation of hypertension.
• Oral contraceptives: reduced effectiveness, advise alternative contraception.