Leflunomide Dosage Guide: Find the Right Amount for Your Condition

Quick Takeaways

• Start most adults with 100 mg daily for 3 days (loading dose) then drop to 20 mg daily.
• Maintain 20 mg daily for rheumatoid arthritis; 10 mg may be enough for milder disease.
• Adjust dose if liver enzymes rise >2× upper limit or if plasma teriflunomide >70 µg/mL.
• Pregnant or breastfeeding patients should avoid leflunomide or undergo an accelerated wash‑out.
• Regular monitoring - CBC, liver panel, and blood pressure - keeps side‑effects in check.

Finding the right amount of leflunomide dosage isn’t just about reading the label. It’s a balancing act between quelling inflammation and steering clear of toxicity. Below you’ll get a clear roadmap: from the basics of what leflunomide is, through standard dose recommendations, to the tweaks you’ll need if you have liver concerns, are pregnant, or are switching from another drug.

What is Leflunomide?

Leflunomide is a disease‑modifying antirheumatic drug (DMARD) that suppresses the immune system by inhibiting dihydroorotate dehydrogenase, an enzyme crucial for pyrimidine synthesis. By cutting off the building blocks for rapidly dividing immune cells, it reduces the joint‑destructive process seen in chronic inflammatory diseases.

How Leflunomide Works - The Active Metabolite

Within hours of ingestion, leflunomide is converted in the liver to Teriflunomide, the pharmacologically active metabolite responsible for most of the drug’s effects. Teriflunomide’s half‑life can stretch to 2 weeks, which explains why dose changes or discontinuation take time to show up in the bloodstream.

Standard Dosing Recommendations

Guidelines from the American College of Rheumatology (2023 update) and the drug’s label converge on a two‑step approach:

1. Loading phase: 100 mg once daily for three consecutive days. This quickly ramps up plasma teriflunomide levels to therapeutic range (≈30‑70 µg/mL).
2. Maintenance phase: 20 mg once daily for most adults. Some patients achieve disease control at 10 mg, especially if they experience mild disease or have a history of liver enzyme elevations.

Typical therapy duration is indefinite, as stopping the drug abruptly can lead to a flare‑up. When a clinician decides to discontinue, a wash‑out protocol with cholestyramine (8 g three times daily for 11 days) or activated charcoal is required to pull teriflunomide out of the body.

Dosage by Indication

While leflunomide is most famous for treating Rheumatoid arthritis, it’s also approved for Psoriatic arthritis. The dosing window is the same, but clinicians may start a bit lower for psoriatic arthritis if skin involvement is the primary concern.

Patients who have already failed Methotrexate often stay on the 20 mg maintenance dose because the two drugs complement each other’s mechanisms.

When to Adjust the Dose

Several patient‑specific factors can push you to tweak the standard schedule:

• Liver function: If alanine aminotransferase (ALT) or aspartate aminotransferase (AST) rise above twice the upper limit of normal (ULN), drop to 10 mg or hold the drug until enzymes normalize.
• Renal impairment: No formal dose reduction, but clinicians often monitor more closely because teriflunomide clearance can be slower.
• Age: Patients >75 years may start directly at 10 mg daily to reduce early toxicity risk.
• Pregnancy: Leflunomide is teratogenic. Women of childbearing potential must use reliable contraception and, if pregnancy occurs, undergo an accelerated wash‑out with cholestyramine.
• Drug interactions: Concomitant use of strong CYP1A2 inducers (e.g., rifampin) can lower teriflunomide levels, potentially necessitating a higher maintenance dose. Conversely, warfarin may have its effect potentiated, requiring closer INR monitoring.

Monitoring Schedule

Regular labs keep the therapy safe. A typical monitoring plan looks like this:

If any test shows abnormal values, adjust the dose or pause therapy per the guidelines above.

Special Situations: Switching Drugs and Wash‑Out

When a patient moves from Methotrexate to leflunomide, there’s no required wash‑out because they act via different pathways. However, the opposite direction-stopping leflunomide to start methotrexate-requires a cholestyramine wash‑out to avoid lingering teriflunomide interference.

For patients who need a rapid removal (e.g., planning pregnancy), cholestyramine 8 g three times daily for 11 days reduces teriflunomide plasma concentration to <10 µg/mL, which is considered safe for conception.

Side‑Effect Profile and What to Watch For

Common adverse events (≥10 % incidence) include diarrhea, rash, and alopecia. More serious concerns are hepatotoxicity and hypertension. If you notice new skin lesions, persistent nausea, or a sudden rise in blood pressure, contact your rheumatologist promptly.

Because teriflunomide can linger for weeks, dose reductions may not immediately lower the risk of toxicity. That’s why the wash‑out protocol is vital when discontinuation is medically necessary.

Frequently Asked Questions

Whether you’re just starting leflunomide or have been on it for years, staying informed about dosage nuances helps you stay in control of your disease and your health.