Leflunomide: uses, appearance and warnings

Leflunomide Tablets are indicated for the treatment of adults with active rheumatoid arthritis (RA). Leflunomide is a pyrimidine synthesis inhibitor indicated for the treatment of adults with active rheumatoid arthritis. ( 1 )

Leflunomide Tablets, USP are available in two strengths: Tablets: 10 mg, supplied as white to off-white, round, biconvex film-coated tablets debossed with "10" on one side and "LFL" on the other side. Tablets: 20 mg, supplied as white to off-white, round, biconvex film-coated tablets debossed with "20" on one side and "LFL" on the other side. Tablets: 10 mg, 20 mg. ( 3 )

How Supplied Leflunomide Tablets, USP Strength Quantity NDC Number Description 10 mg 30 count bottle 35573-447-30 White to off-white, round, biconvex film-coated tablets debossed with "10" on one side and "LFL" on the other side. 20 mg 30 count bottle 35573-448-30 White to off-white, round, biconvex film-coated tablets debossed with "20" on one side and "LFL" on the other side. TAMPER EVIDENT: Do not use if ring below the closure is broken or missing. CHILD RESISTANT: This package features a child-resistant closure. Store at 20°C to 25°C (68°F to 77°F); excursions permitted to 15°C to 30°C (59°F to 86°F) [see USP Controlled Room Temperature]. Protect from light.

Leflunomide is contraindicated in: Pregnant women. Leflunomide may cause fetal harm. If a woman becomes pregnant while taking this drug, stop leflunomide, apprise the patient of the potential hazard to the fetus, and begin a drug elimination procedure [see Warnings and Precautions (5.1 , 5.3) and Use in Specific Populations (8.1) ]. Patients with severe hepatic impairment [see Warnings and Precautions (5.2) ]. Patients with known hypersensitivity to leflunomide or any of the other components of leflunomide. Known reactions include anaphylaxis [see Adverse Reactions (6.1) ]. Patients being treated with teriflunomide [see Drug Interactions (7) ]. Pregnancy. ( 4 , 5.1 , 8.1 ) Severe hepatic impairment. ( 4 , 5.2 ) Hypersensitivity to leflunomide or any of its inactive components. ( 4 ) Current teriflunomide treatment. ( 4 )

After stopping leflunomide, it is recommended that an accelerated drug elimination procedure be used to reduce the plasma concentrations of the active metabolite, teriflunomide. ( 5.3 ) Severe infections (including sepsis), pancytopenia, agranulocytosis, and thrombocytopenia: Stop leflunomide and use accelerated elimination procedure. Do not start leflunomide in patients with active infection. Monitor CBCs during treatment with leflunomide. ( 5.4 ) Stevens-Johnson syndrome and toxic epidermal necrolysis, drug reaction with eosinophilia and systemic symptoms (DRESS): Stop leflunomide and use accelerated elimination procedure. ( 5.5 ) Skin ulcers: If skin ulcer is suspected, discontinue leflunomide treatment and consider an accelerated drug elimination procedure. ( 5.6 ) Peripheral neuropathy: If patient develops symptoms consistent with peripheral neuropathy, evaluate patient and consider discontinuing leflunomide. ( 5.8 ) Interstitial lung disease: May be fatal. New onset or worsening symptoms may necessitate discontinuation of leflunomide and initiation of accelerated elimination procedure. ( 5.9 ) Increased blood pressure: Monitor and treat. ( 5.11 ) 5.1 Embryo-Fetal Toxicity Leflunomide may cause fetal harm when administered to a pregnant woman. Teratogenicity and embryo-lethality occurred in animal reproduction studies with leflunomide at doses lower than the human exposure level [see Use in Specific Populations (8.1) ]. Leflunomide is contraindicated for use in pregnant women [see Contraindications (4) ] . Exclude pregnancy before starting treatment with leflunomide in females of reproductive potential [see Dosage and Administration (2.2) ] . Advise females of reproductive potential to use effective contraception during leflunomide treatment and during an accelerated drug elimination procedure after leflunomide treatment [see Use in Specific Populations (8.3) ] . If a woman becomes pregnant while taking leflunomide, stop treatment with leflunomide, apprise the patient of the potential risk to a fetus, and perform an accelerated drug elimination procedure to achieve nondetectable plasma concentrations of teriflunomide, the active metabolite of leflunomide [see Warnings and Precautions (5.3) ]. Upon discontinuing leflunomide, it is recommended that all females of reproductive potential undergo an accelerated drug elimination procedure. Women receiving leflunomide treatment who wish to become pregnant must discontinue leflunomide and undergo an accelerated drug elimination procedure, which includes verification that plasma concentrations of the active metabolite of leflunomide, teriflunomide, are less than 0.02 mg/L (0.02 mcg/mL). Based on animal data, human plasma concentrations of teriflunomide of less than 0.02 mg/L (0.02 mcg/mL) are expected to have minimal embryo-fetal risk [see Contraindications (4) , Warnings and Precautions (5.3) , and Use in Specific Populations (8.1) ] . 5.2 Hepatotoxicity Severe liver injury, including fatal liver failure, has been reported in some patients treated with leflunomide. Patients with pre-existing acute or chronic liver disease, or those with serum alanine aminotransferase (ALT) of greater than twice the upper limits of normal (>2 × ULN) before initiating treatment, should not be treated with leflunomide. Use caution when leflunomide is given with other potentially hepatotoxic drugs. Monitoring of ALT levels is recommended at least monthly for six months after starting leflunomide, and thereafter every 6 to 8 weeks. If ALT elevation >3-fold ULN occurs, interrupt leflunomide therapy and investigate the cause. If likely leflunomide-induced, perform the accelerated drug elimination procedure and monitor liver tests weekly until normalized [see Warnings and Precautions (5.3) ]. If leflunomide-induced liver injury is unlikely because some other cause has been found, resumption of leflunomide therapy may be considered. If leflunomide and methotrexate are given concomitantly, follow the American College of Rheumatology (ACR) guidelines for monitoring methotrexate liver toxicity with ALT, AST, and serum albumin testing. 5.3 Procedure for Accelerated Elimination of Leflunomide and its Active Metabolite The active metabolite of leflunomide, teriflunomide, is eliminated slowly from the plasma [see Clinical Pharmacology (12.3) ] . Use of an accelerated drug elimination procedure will rapidly reduce plasma concentrations of leflunomide and its active metabolite, teriflunomide. Therefore, an accelerated elimination procedure should be considered at any time after discontinuation of leflunomide, and in particular, when a patient has experienced a severe adverse reaction (e.g., hepatotoxicity, serious infection, bone marrow suppression, Stevens-Johnson Syndrome, toxic epidermal necrolysis, peripheral neuropathy, interstitial lung disease), suspected hypersensitivity, or has become pregnant. It is recommended that all women of childbearing potential undergo an accelerated elimination procedure after stopping leflunomide treatment. Without use of an accelerated drug elimination procedure, it may take up to 2 years to reach plasma teriflunomide concentrations of less than 0.02 mg/L, the plasma concentration not associated with embryo-fetal toxicity in animals. Elimination can be accelerated by the following procedures: Administer cholestyramine 8 grams orally 3 times daily for 11 days. Alternatively, administer 50 grams of activated charcoal powder (made into a suspension) orally every 12 hours for 11 days. Verify plasma teriflunomide concentrations of less than 0.02 mg/L (0.02 µg/mL) by two separate tests at least 14 days apart. If plasma teriflunomide concentrations are higher than 0.02 mg/L, repeat cholestyramine and/or activated charcoal treatment. The duration of accelerated drug elimination treatment may be modified based on the clinical status and tolerability of the elimination procedure. …

The following serious adverse reactions are described elsewhere in the labeling: Hepatotoxicity [see Warnings and Precautions (5.2) ] Immunosuppression [see Warnings and Precautions (5.4) ] Bone marrow suppression [see Warnings and Precautions (5.4) ] Serious infections [see Warnings and Precautions (5.4) ] Stevens-Johnson syndrome, toxic epidermal necrolysis, and drug reactions with eosinophilia and systemic symptoms [see Warnings and Precautions (5.5) ] Skin ulcers [see Warnings and Precautions (5.6) ] Peripheral neuropathy [see Warnings and Precautions (5.8) ] Interstitial lung disease [see Warnings and Precautions (5.9) ] The most commonly reported adverse reactions (≥10%) regardless of relation to leflunomide treatment were diarrhea, respiratory infection, nausea, headache, rash, abnormal liver enzymes, and dyspepsia. …

Following oral administration, leflunomide is metabolized to an active metabolite, teriflunomide, which is responsible for essentially all of leflunomide's in vivo activity. Drug interaction studies have been conducted with both leflunomide and with its active metabolite, teriflunomide, where the metabolite was directly administered to the test subjects. Drugs metabolized by CYP2C8 and OAT3 transporters: Monitor patients because teriflunomide may increase exposure of these drugs. ( 7 ) Teriflunomide may increase exposure of ethinylestradiol and levonorgestrel. Choose an appropriate oral contraceptive. ( 7 ) Drugs metabolized by CYP1A2: Monitor patients because teriflunomide may decrease exposure of these drugs. ( 7 ) Warfarin: Monitor INR as teriflunomide may decrease INR. …