leflunomide 20 MG Oral Tablet [Arava]

INDICATIONS AND USAGE Leflunomide Tablets, USP are indicated for the treatment of adults with active rheumatoid arthritis (RA). Leflunomide tablets are a pyrimidine synthesis inhibitor indicated for the treatment of adults with active rheumatoid arthritis. ( 1 )

DOSAGE AND ADMINISTRATION Loading dosage for patients at low risk for leflunomide tablets -associated hepatotoxicity and leflunomide tablets-associated myelosuppression: 100 mg daily for 3 days. ( 2.1 ) Maintenance dosage: 20 mg daily. ( 2.1 ) Maximum recommended daily dosage: 20 mg once daily. ( 2.1 ) If 20 mg once daily is not tolerated, may decrease dosage to 10 mg once daily. ( 2.1 ) Screen patients for active and latent tuberculosis, pregnancy test (females), blood pressure, and laboratory tests before starting leflunomide tablets. ( 2.2 ) 2.1 Recommended Dosage The recommended dosage of leflunomide tablets is 20 mg once daily. Treatment may be initiated with or without a loading dose, depending upon the patient's risk of leflunomide tablets -associated hepatotoxicity and leflunomide tablets -associated myelosuppression. The loading dose provides steady-state concentrations more rapidly. For patients who are at low risk for leflunomide tablets -associated hepatotoxicity and leflunomide tablets - associated myelosuppression, the recommended leflunomide tablets loading dose is 100 mg once daily for 3 days. Subsequently administer 20 mg once daily. For patients at high risk for leflunomide tablets - associated hepatotoxicity (e.g., those taking concomitant methotrexate) or leflunomide tablets -associated myelosuppression (e.g., patients taking concomitant immunosuppressants), the recommended leflunomide tablets dosage is 20 mg once daily without a loading dose [see Warnings and Precautions ( 5.2 , 5.4 )]. The maximum recommended daily dose is 20 mg once per day. Consider dosage reduction to 10 mg once daily for patients who are not able to tolerate 20 mg daily (i.e., for patients who experience any adverse events listed in Table 1). Monitor patients carefully after dosage reduction and after stopping therapy with leflunomide tablets, since the active metabolite of leflunomide, teriflunomide, is slowly eliminated from the plasma [ see Clinical Pharmacology ( 12.3 ) ]. After stopping leflunomide tablets treatment, an accelerated drug elimination procedure is recommended to reduce the plasma concentrations of the active metabolite, teriflunomide [see Warnings and Precautions ( 5.3 )]. Without use of an accelerated drug elimination procedure, it may take up to 2 years to reach undetectable plasma teriflunomide concentrations after stopping leflunomide tablets [see Clinical Pharmacology ( 12.3 )]. 2.2 Evaluation and Testing Prior to Starting leflunomide tablets Prior to starting leflunomide tablets treatment, the following evaluations and tests are recommended: Evaluate patients for active tuberculosis and screen patients for latent tuberculosis infection [see Warnings and Precautions ( 5.4 )] Laboratory tests including serum alanine aminotransferase (ALT); and white blood cell, hemoglobin or hematocrit, and platelet counts [see Warnings and Precautions ( 5.2 , 5.4 )] For females of reproductive potential, pregnancy testing [see Warnings and Precautions ( 5.1 )] Check blood pressure [see Warnings and Precautions ( 5.11 )]

WARNINGS AND PRECAUTIONS 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: Stop leflunomide and use accelerated elimination procedure. ( 5.5 ) Peripheral neuropathy: If patient develops symptoms consistent with peripheral neuropathy evaluate patient and consider discontinuing leflunomide. ( 5.7 ) Interstitial lung disease: May be fatal. New onset or worsening symptoms may necessitate discontinuation of leflunomide and initiation of accelerated elimination procedure. ( 5.8 ) Increased blood pressure: Monitor and treat. ( 5.10 ) 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 non-detectable 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 (>2xULN) 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, Steven 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: 1) Administer cholestyramine 8 grams orally 3 times daily for 11 days. 2) 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 procedure may be repeated as needed, based on teriflunomide concentrations and clinical status. Use of the accelerated drug elimination procedure may potentially result in return of disease activity if the patient had been responding to leflunomide treatment. 5.4 Immunosuppression, Bone Marrow Suppression, and Risk of Serious Infections Leflunomide is not recommended for patients with severe immunodeficiency, bone marrow dysplasia, or severe, uncontrolled infections. If a serious infection occurs, consider interrupting leflunomide therapy and initiating the accelerated drug elimination procedure [see Warnings and Precautions (5.3) ]. Medications like leflunomide that have immunosuppression potential may cause patients to be more susceptible to infections, including opportunistic infections, especially Pneumocystis jiroveci pneumonia, tuberculosis (including extra-pulmonary tuberculosis), and aspergillosis. Severe infections including sepsis, which may be fatal, have been reported in patients receiving leflunomide, especially Pneumocystis jiroveci pneumonia and aspergillosis. Most of the reports were confounded by concomitant immunosuppressant therapy and/or comorbid illness which, in addition to rheumatoid arthritis, may predispose patients to infection. Cases of tuberculosis were observed in clinical studies with teriflunomide, the metabolite of leflunomide. Prior to initiating leflunomide, all patients should be screened for active and inactive ("latent") tuberculosis infection as per commonly used diagnostic tests. Leflunomide has not been studied in patients with a positive tuberculosis screen, and the safety of leflunomide in individuals with latent tuberculosis infection is unknown. Patients testing positive in tuberculosis screening should be treated by standard medical practice prior to therapy with leflunomide and monitored carefully during leflunomide treatment for possible reactivation of the infection. Pancytopenia, agranulocytosis and thrombocytopenia have been reported in patients receiving leflunomide alone. These events have been reported most frequently in patients who received concomitant treatment with methotrexate or other immunosuppressive agents, or who had recently discontinued the

CONTRAINDICATIONS Leflunomide tablet is contraindicated in: Pregnant women. Leflunomide tablets may cause fetal harm. If a woman becomes pregnant while taking this drug, stop leflunomide tablets, 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 tablets. 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 tablets or any of its inactive components. ( 4 ) Current teriflunomide treatment. ( 4 )

CLINICAL PHARMACOLOGY 12.1 Mechanism of Action Leflunomide is an isoxazole immunomodulatory agent that inhibits dihydroorotate dehydrogenase (a mitochondrial enzyme involved in de novo pyrimidine synthesis) and has antiproliferative activity. Several in vivo and in vitro experimental models have demonstrated an anti-inflammatory effect. 12.3 Pharmacokinetics Following oral administration, leflunomide is metabolized to an active metabolite, teriflunomide, which is responsible for essentially all of leflunomide's in vivo activity. Plasma concentrations of the parent drug, leflunomide, have been occasionally seen at very low concentrations. Studies of the pharmacokinetics of leflunomide have primarily examined the plasma concentrations of the active metabolite, teriflunomide. Absorption Following oral administration, peak teriflunomide concentrations occurred between 6 to 12 hours after dosing. Due to the very long half-life of teriflunomide (18 to 19 days), a loading dose of 100 mg for 3 days was used in clinical studies to facilitate the rapid attainment of steady-state teriflunomide concentrations. Without a loading dose, it is estimated that attainment of steady- state plasma concentrations would require about two months of dosing. The resulting plasma concentrations following both loading doses and continued clinical dosing indicate that plasma teriflunomide concentrations are dose proportional. Effect of food Coadministration of leflunomide tablets with a high fat meal did not have a significant impact on teriflunomide plasma concentrations. Distribution Teriflunomide is extensively bound to plasma protein (>99%) and is mainly distributed in plasma. The volume of distribution is 11 L after a single intravenous (IV) administration. Elimination Teriflunomide, the active metabolite of leflunomide, has a median half-life of 18 to 19 days in healthy volunteers. The elimination of teriflunomide can be accelerated by administration of cholestyramine or activated charcoal. 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, due to individual variation in drug clearance [see Warnings and Precautions (5.3) ] . After a single IV administration of the metabolite (teriflunomide), the total body clearance of teriflunomide was 30.5 mL/h. Metabolism In vitro inhibition studies in human liver microsomes suggest that cytochrome P450 (CYP) 1A2, 2C19 and 3A4 are involved in leflunomide metabolism. In vivo , leflunomide is metabolized to one primary (teriflunomide) and many minor metabolites. In vitro , teriflunomide is not metabolized by CYP450 or flavin monoamine oxidase enzymes. The parent compound is rarely detectable in plasma. Excretion Teriflunomide, the active metabolite of leflunomide, is eliminated by direct biliary excretion of unchanged drug as well as renal excretion of metabolites. Over 21 days, 60.1% of the administered dose is excreted via feces (37.5%) and urine (22.6%). After an accelerated elimination procedure with cholestyramine, an additional 23.1% was recovered (mostly in feces). Studies with both hemodialysis and CAPD (chronic ambulatory peritoneal dialysis) indicate that teriflunomide is not dialyzable. Specific Populations Gender. Gender has not been shown to cause a consistent change in the in vivo pharmacokinetics of teriflunomide. Smoking. A population based pharmacokinetic analysis of the clinical trial data indicates that smokers have a 38% increase in clearance over nonsmokers; however, no difference in clinical efficacy was seen between smokers and nonsmokers. Drug Interaction Studies 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. The potential effect of other drugs on leflunomide • Potent CYP and transporter inducers: Following concomitant administration of a single dose of leflunomide to subjects receiving multiple doses of rifampin, teriflunomide peak concentrations were increased (~40%) over those seen when leflunomide was given alone [see Drug Interactions (7) ] . • An in vivo interaction study with leflunomide and cimetidine (nonspecific weak CYP inhibitor) has demonstrated a lack of a significant impact on teriflunomide exposure. The Potential Effect of leflunomide on Other Drugs • CYP2C8 Substrates There was an increase in mean repaglinide C max and AUC (1.7 and 2.4-fold, respectively), following repeated doses of teriflunomide and a single dose of 0.25 mg repaglinide, suggesting that teriflunomide is an inhibitor of CYP2C8 in vivo . The magnitude of interaction could be higher at the recommended repaglinide dose [see Drug Interactions (7) ] . • CYP1A2 Substrates Repeated doses of teriflunomide decreased mean C max and AUC of caffeine by 18% and 55%, respectively, suggesting that teriflunomide may be a weak inducer of CYP1A2 in vivo . • OAT3 Substrates There was an increase in mean cefaclor C max and AUC (1.43 and 1.54-fold, respectively), following repeated doses of teriflunomide, suggesting that teriflunomide is an inhibitor of organic anion transporter 3 (OAT3) in vivo [see Drug Interactions (7) ] . • BCRP and OATP1B1/1B3 Substrates There was an increase in mean rosuvastatin C max and AUC (2.65 and 2.51-fold, respectively), following repeated doses of teriflunomide, suggesting that teriflunomide is an inhibitor of BCRP transporter and organic anion transporting polypeptide 1B1 and 1B3 (OATP1B1/1B3) [see Drug Interactions (7) ] . • Oral Contraceptives There was an increase in mean ethinylestradiol C max and AUC 0-24 (1.58 and 1.54-fold, respectively) and levonorgestrel C max and AUC 0-24 (1.33 and 1.41-fold, respectively) following repeated doses of teriflunomide [see Drug Interactions (7)]. • Teriflunomide did not affect the pharmacokinetics of bupropion (a CYP2B6 substrate), midazolam (a CYP3A4 substrate), S-warfarin (a CYP2C9 substrate), omeprazole (a CYP2C19 substrate), and metoprolol (a CYP2D6 substrate). teriflunomide-structural-formula.