Leflunomide Normon (Leflunomide)

Leflunomide is a disease‑modifying antirheumatic drug used to manage inflammatory joint disorders.

• Rheumatoid arthritis: reduces joint inflammation, pain and slows structural damage.
• Psoriatic arthritis: improves skin lesions and joint symptoms, helping maintain function.
• Active rheumatoid arthritis: assists in achieving disease remission and better quality of life.

• Leflunomide inhibits the mitochondrial enzyme dihydroorotate dehydrogenase, which blocks de novo pyrimidine synthesis. This limits the proliferation of activated lymphocytes, thereby reducing the autoimmune response that drives joint inflammation in rheumatoid and psoriatic arthritis.

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

Common Side Effects

• Diarrhea: mild to moderate gastrointestinal upset.
• Nausea: occasional feeling of queasiness.
• Headache: transient cranial discomfort.
• Hypertension: elevation of blood pressure.
• Alopecia: thinning or loss of hair.
• Rash: mild skin irritation.

Serious or Rare Side Effects

• Hepatotoxicity: elevated liver enzymes or liver injury.
• Severe infections: increased susceptibility to bacterial or viral infections.
• Pulmonary toxicity: interstitial lung disease or pneumonitis.
• Bone marrow suppression: anemia, leukopenia, or thrombocytopenia.
• Stevens‑Johnson syndrome: severe skin reactions.
• Teratogenicity: risk of fetal harm if exposure occurs during pregnancy.

Before initiating therapy, clinicians should assess baseline health and monitor for specific risks.

• Liver function monitoring: perform baseline and periodic liver enzyme tests.
• Blood pressure control: check and manage hypertension regularly.
• Pregnancy avoidance: contraindicated in pregnancy; ensure effective contraception.
• Infection surveillance: evaluate for active infections before and during treatment.
• Drug-specific counseling: advise patients about potential hair loss and rash.
• Store at below 25°C: keep in the original packaging, protect from moisture and direct sunlight.

Leflunomide can alter the activity of several concomitant medications.

Major Interactions (Avoid)

• Warfarin: may increase anticoagulant effect and INR.
• Methotrexate: combined use can heighten hepatotoxicity and bone‑marrow suppression.
• Cholesterol‑binding resins (e.g., cholestyramine): reduce leflunomide exposure.

Moderate Interactions (Monitor Closely)

• Statins: increased risk of myopathy.
• Oral contraceptives: possible reduction in contraceptive efficacy; consider alternative methods.