Which statement describes Leflunomide's half-life?

• A. Long half-life.
• B. Short half-life.
• C. Half-life varies with meals.
• D. No significant half-life.

Answer: (A)

Leflunomide has a long terminal half-life because its active metabolite teriflunomide undergoes extensive enterohepatic recirculation. After dosing, teriflunomide is excreted into bile, reabsorbed from the gut, and kept in circulation for an extended period, so it takes weeks to months for levels to fall after stopping the drug. The half-life is not significantly affected by meals; meal timing doesn’t shorten or lengthen how long the drug stays in the body. Therefore, describing its half-life as long best fits its pharmacokinetic profile, whereas options implying a short half-life, variability with meals, or no significant half-life don’t align with how this drug is eliminated. In practice, this long persistence explains why accelerated elimination with cholestyramine or activated charcoal can be used if rapid clearance is needed.