Leflunomid Hexal (Leflunomide)

Leflunomide is a disease‑modifying antirheumatic drug (DMARD) that acts on the immune system to control inflammatory arthritis.

• Rheumatoid arthritis: reduces joint inflammation, pain, and slows structural damage.
• Psoriatic arthritis: improves joint symptoms and may benefit associated skin lesions.
• Inadequate response to other DMARDs: provides an alternative therapeutic option for patients whose disease remains active despite prior treatment.

• Leflunomide is converted in vivo to its active metabolite teriflunomide, which selectively inhibits the mitochondrial enzyme dihydroorotate dehydrogenase. This blockade impairs de novo pyrimidine synthesis, limiting the proliferation of activated T‑lymphocytes and B‑cells. The resulting reduction in lymphocyte expansion diminishes the autoimmune inflammatory response that drives joint damage in rheumatoid and psoriatic arthritis. By targeting this pathway, leflunomide exerts a cytostatic effect without broadly suppressing other cellular functions.

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

Common Side Effects

• Diarrhea: mild to moderate gastrointestinal upset.
• Nausea: occasional feeling of sickness.
• Elevated liver enzymes: transient increase in hepatic transaminases.
• Hypertension: rise in blood pressure readings.

Serious or Rare Side Effects

• Hepatotoxicity: severe liver injury or failure.
• Severe infections: opportunistic or bacterial infections requiring medical attention.
• Pulmonary toxicity: interstitial lung disease or pneumonitis.
• Stevens‑Johnson syndrome/TEN: severe skin reactions with mucosal involvement.

When prescribing leflunomide, clinicians should observe several precautionary measures to minimize risk.

• Liver monitoring: perform baseline and periodic liver function tests.
• Pregnancy avoidance: contraindicated in pregnancy; ensure effective contraception.
• Teratogenic risk: advise women of child‑bearing potential about birth control.
• Blood pressure: monitor for hypertension during therapy.
• Infection vigilance: assess for signs of serious infection before and during treatment.
• Store at below 25°C: keep in the original packaging, protect from moisture and heat.

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

Major Interactions (Avoid)

• Teratogenic agents: concurrent use may increase risk of fetal harm.
• Strong CYP1A2 inhibitors (e.g., fluvoxamine): can raise leflunomide plasma levels.
• Azathioprine: combined immunosuppression may heighten infection risk.

Moderate Interactions (Monitor Closely)

• Statins: may increase risk of muscle toxicity.
• Oral contraceptives: leflunomide can reduce hormonal efficacy.
• Methotrexate: combined use may enhance hepatotoxicity.