Leflunomide

Warnings and Precautions, Skin Ulcers (5.6) ................................................................................................................... 6/2024

1 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 )

2 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 are 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 dosage 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 dosage 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 dosage 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 (5.10) ]

3 DOSAGE FORMS AND STRENGTHS Leflunomide tablets USP are available in two strengths: · Tablets: 10 mg, supplied as white to off white, circular, biconvex, film coated tablets debossed with ‘L115’ on one side and plain on the other side · Tablets: 20 mg, supplied as yellow colored, triangular, biconvex, film coated tablets debossed with ‘L116’ on one side and plain on the other side Tablets: 10 mg, 20 mg ( 3 )

4 CONTRAINDICATIONS Leflunomide Tablets are 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 and 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)

6 ADVERSE REACTIONS 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 )] Stevens-Johnson syndrome and toxic epidermal necrolysis [see Warnings and Precautions ( 5.5 )] Peripheral neuropathy [see Warnings and Precautions ( 5.7 )] Interstitial lung disease [see Warnings and Precautions ( 5.8 )] The most commonly reported adverse reactions (≥10%) regardless of relation to leflunomide treatment were diarrhea, respiratory infection, nausea, headache, rash, abnormal liver enzymes, dyspepsia. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact AvKARE at 1-855-361-3993 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical studies are conducted under widely varying conditions, adverse reaction rates observed in the clinical studies of a drug cannot be directly compared to rates in the clinical studies of another drug and may not reflect the rates observed in practice. In clinical studies (Trials 1, 2, and 3), 1,865 patients were treated with leflunomide administered as either monotherapy or in combination with methotrexate or sulfasalazine. Patients ranged in age from 19 to 85 years, with an overall median age of 58 years. The mean duration of RA was 6 years ranging from 0 to 45 years. Elevation of Liver Enzymes Treatment with leflunomide was associated with elevations of liver enzymes, primarily ALT and AST, in a significant number of patients; these effects were generally reversible. Most transaminase elevations were mild (≤ 2-fold ULN) and usually resolved while continuing treatment. Marked elevations (>3-fold ULN) occurred infrequently and reversed with dose reduction or discontinuation of treatment. Table 1 shows liver enzyme elevations seen with monthly monitoring in clinical trials Trial 1 and Trial 2. It was notable that the absence of folate use in Trial 3 was associated with a considerably greater incidence of liver enzyme elevation on methotrexate. Table 1. Liver Enzyme Elevations >3-fold Upper Limits of Normal (ULN) in Patients with RA in Trials 1, 2, and 3** Trial 1 Trial 2 Trial 3* Leflunomide 20 mg/day (n= 182) PL(n=118) MTX 7.5 – 15 mg/wk (n=182) Leflunomide 20mg/day (n=133) PL(n=92) SSZ 2.0 g/day (n=133) Leflunomide 20 mg/day (n=501) MTX 7.5 – 15 mg/wk (n=498) ALT (SGPT)>3-fold ULN (n%) Reversed to ≤ 2-fold ULN: 8(4.4) 8 3(2.5) 3 5(2.7) 5 2(1.5) 2 1(1.1) 1 2(1.5) 2 13(2.6) 12 83 (16.7) 82 Timing of Elevation 6 1 1 2 1 2 7 27 0-3 Months 4-6 Months 1 1 3 - - - 1 34 7-9 Months 1 1 1 - - - - 16 10-12 Months - - - - - - 5 6 MTX = methotrexate, PL = placebo, SSZ = sulfasalazine, ULN = Upper limit of normal * Only 10% of patients in Trial 3 received folate. All patients in Trial 1 received folate. In a 6 month study of 263 patients with persistent active rheumatoid arthritis despite methotrexate therapy, and with normal LFTs, leflunomide was administered to a group of 130 patients starting at 10 mg per day and increased to 20 mg as needed. An increase in ALT greater than or equal to three times the ULN was observed in 3.8% of patients compared to 0.8% in 133 patients continued on methotrexate with placebo. Most Common Adverse Reactions The most common adverse reactions in leflunomide-treated patients with RA include diarrhea, elevated liver enzymes (ALT and AST), alopecia and rash. Table 2 displays the most common adverse reactions in the controlled studies in patients with RA at one year (≥5% in any leflunomide treatment group). Table 2. Percentage Of Patients With Adverse Events ≥5% In Any Leflunomide Treated Group in all RA Studies in Patients with RA Placebo-Controlled Trials Active-Controlled Trials All RA Studies Trial 1 and 2 Trial 3 1 Leflunomide 20 mg/day (N=315) PL (N=210) SSZ 2.0g/day (N=133) MTX 7.5 – 15 mg/wk (N=182) Leflunomide 20 mg/day (N=501) MTX 7.5 – 15 mg/wk (N= …

7 DRUG INTERACTIONS 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 tablets (leflunomide) and with its active metabolite, teriflunomide, where the metabolite was directly administered to the test subjects. Effect of potent CYP and transporter inducers Leflunomide is metabolized by CYP450 metabolizing enzymes. Concomitant use of leflunomide tablets and rifampin, a potent inducer of CYP and transporters, increased the plasma concentration of teriflunomide by 40%. However, when co-administered with the metabolite, teriflunomide, rifampin did not affect its pharmacokinetics. No dosage adjustment is recommended for leflunomide tablets when coadministered with rifampin. Because of the potential for leflunomide tablets concentrations to continue to increase with multiple dosing, caution should be used if patients are to be receiving both leflunomide tablets and rifampin [ see Clinical Pharmacology (12.3) ]. Effect on CYP2C8 substrates Teriflunomide is an inhibitor of CYP2C8 in vivo . In patients taking leflunomide tablets, exposure of drugs metabolized by CYP2C8 (e.g., paclitaxel, pioglitazone, repaglinide, rosiglitazone) may be increased. Monitor these patients and adjust the dose of the concomitant drug(s) metabolized by CYP2C8 as required [ see Clinical Pharmacology (12.3) ]. Effect on warfarin Coadministration of leflunomide tablets with warfarin requires close monitoring of the international normalized ratio (INR) because teriflunomide, the active metabolite of leflunomide tablets, may decrease peak INR by approximately 25%. Effect on oral contraceptives Teriflunomide may increase the systemic exposures of ethinylestradiol and levonorgestrel. Consideration should be given to the type or dose of contraceptives used in combination with leflunomide tablets [ see Clinical Pharmacology (12.3) ]. Effect on CYP1A2 substrates Teriflunomide, the active metabolite of leflunomide tablets, may be a weak inducer of CYP1A2 in vivo . In patients taking leflunomide tablets, exposure of drugs metabolized by CYP1A2 (e.g., alosetron, duloxetine, theophylline, tizanidine) may be reduced. Monitor these patients and adjust the dose of the concomitant drug(s) metabolized by CYP1A2 as required [ see Clinical Pharmacology (12.3) ]. Effect on organic anion transporter 3 (OAT3) substrates Teriflunomide inhibits the activity of OAT3 in vivo . In patients taking leflunomide tablets, exposure of drugs which are OAT3 substrates (e.g., cefaclor, cimetidine, ciprofloxacin, penicillin G, ketoprofen, furosemide, methotrexate, zidovudine) may be increased. Monitor these patients and adjust the dose of the concomitant drug(s) which are OAT3 substrates as required [ see Clinical Pharmacology (12.3) ]. Effect on BCRP and organic anion transporting polypeptide B1 and B3 (OATP1B1/1B3) substrates Teriflunomide inhibits the activity of BCRP and OATP1B1/1B3 in vivo. For a patient taking leflunomide tablets, the dose of rosuvastatin should not exceed 10 mg once daily. For other substrates of BCRP (e.g., mitoxantrone) and drugs in the OATP family (e.g., methotrexate, rifampin), especially HMG-Co reductase inhibitors (e.g., atorvastatin, nateglinide, pravastatin, repaglinide, and simvastatin), consider reducing the dose of these drugs and monitor patients closely for signs and symptoms of increased exposures to the drugs while patients are taking leflunomide tablets [ see Clinical Pharmacology (12.3) ]. 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 …

8 USE IN SPECIFIC POPULATIONS Lactation: Discontinue breastfeeding. ( 8.2 ) Females and males of Reproductive Potential: See FPI for information regarding contraception. (8.3) Safety and effectiveness in pediatric patients <12 years of age has not been established. ( 8.4 ) 8.1 Pregnancy Pregnancy Exposure Registry There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to leflunomide during pregnancy. Health care providers and patients are encouraged to report pregnancies by calling 1-877-311-8972 or visit http://www.pregnancystudies.org/participate-in­-a-study/. Risk Summary Leflunomide is contraindicated for use in pregnant women because of the potential for fetal harm. In animal reproduction studies, oral administration of leflunomide during organogenesis at a dose of 1/10 of, and equivalent to, the maximum recommended human dose (MRHD) based on AUC, respectively, in rats and rabbits, caused teratogenicity (rats and rabbits), and embryo-lethality (rats) [see Data] . Pregnancy exposure registry data are not available at this time to inform the presence or absence of drug-associated risk with the use of leflunomide during pregnancy. The background risk of major birth defects and miscarriage for the indicated populations is unknown. The background risk in the U.S. general population of major birth defects is 2-4% and of miscarriage is 15-20% of clinically recognized pregnancies. If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, stop treatment with leflunomide, apprise the patient of the potential hazard to a fetus, and perform the accelerated drug elimination procedure to achieve teriflunomide concentrations of less than 0.02 mg/L (0.02 mcg/mL) [see Warnings and Precautions ( 5.3 )]. Clinical Considerations Fetal/Neonatal adverse reactions Lowering the plasma concentration of the active metabolite, teriflunomide, by instituting an accelerated drug elimination procedure as soon as pregnancy is detected may decrease the risk to the fetus from leflunomide. The accelerated drug elimination procedure includes verification that the plasma teriflunomide concentration is less than 0.02 mg/L [see Warnings and Precautions ( 5.3 ) and Clinical Pharmacology ( 12.3 )]. Data Animal data In an embryofetal development study, pregnant rats administered leflunomide during organogenesis from gestation days 7 to 19 at a dose approximately 1/10 of the MRHD (on an AUC basis at a maternal oral dose of 15 mg/kg), teratogenic effects, most notably anophthalmia or microphthalmia and internal hydrocephalus, were observed. Under these exposure conditions, leflunomide also caused a decrease in the maternal body weight and an increase in embryolethality with a decrease in fetal body weight for surviving fetuses. In an embryo-fetal development study, pregnant rabbits administered leflunomide during organogenesis from gestation days 6 to 18 at a dose approximately equivalent to the MRHD (on an AUC basis at a maternal oral dose of 10 mg/kg), a teratogenic finding of fused, dysplastic sternebrae was observed. Leflunomide was not teratogenic in rats and rabbits at doses approximately 1/150 and 1/10 of the MRHD, respectively (on an AUC basis at maternal oral dose of 1 mg/kg in both rats and rabbits). In a pre and post-natal development study, when female rats were treated with leflunomide at a dose that was approximately 1/100 of the MRHD (on an AUC basis at a maternal dose of 1.25 mg/kg) beginning 14 days before mating and continuing until the end of lactation, the offspring exhibited marked (greater than 90%) decreases in postnatal survival. 8.2 Lactation Risk Summary Clinical lactation studies have not been conducted to assess the presence of leflunomide in human milk, the effects of leflunomide on the breastfed child, or the effects of leflunomide on milk production. Because of the potential for serious adverse reactions in a breastfed infant from leflunomide, advise a nursing w …

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.

11 DESCRIPTION Leflunomide is a pyrimidine synthesis inhibitor. The chemical name for leflunomide is 4-Isoxazolecarboxamide, 5-methyl-N-[4-(trifluoromethyl)-phenyl]-. It has an empirical formula C12H9F3N2O2, a molecular weight of 270.21 and the following structural formula: Leflunomide tablets are available for oral administration as film coated tablets containing 10, or 20 mg of active drug. Combined with leflunomide are the following inactive ingredients: colloidal silicon dioxide, crospovidone, hypromellose, lactose monohydrate, magnesium stearate, polyethylene glycol, povidone, corn starch, talc, titanium dioxide, and yellow ferric oxide (20 mg tablet only). chemicalstructure

10 OVERDOSAGE There have been reports of chronic overdose in patients taking leflunomide tablets at daily dose up to five times the recommended daily dose and reports of acute overdose in adults and children. Adverse events were consistent with the safety profile for leflunomide tablets [ See Adverse Reactions (6) ]. The most frequent adverse events observed were diarrhea, abdominal pain, leukopenia, anemia and elevated liver function tests. In the event of a significant overdose or toxicity, perform an accelerated drug elimination procedure to accelerate elimination [ see Warnings and Precautions (5.3) ]. Studies with both hemodialysis and CAPD (chronic ambulatory peritoneal dialysis) indicate that teriflunomide, the primary metabolite of leflunomide, is not dialyzable [ s ee Clinical Pharmacology (12.3) ].

16 HOW SUPPLIED/STORAGE AND HANDLING How Supplied Leflunomide tablets USP, 10 mg are white to off white, circular, biconvex, film coated tablets debossed with ‘L115’ on one side and plain on the other side, and are supplied as follows: NDC 46708-436-30 bottles of 30 tablets NDC 46708-436-60 bottles of 60 tablets NDC 46708-436-31 bottles of 100 tablets NDC 46708-436-71 bottles of 500 tablets Leflunomide tablets USP, 20 mg are yellow colored, triangular, biconvex, film coated tablets debossed with ‘L116’ on one side and plain on the other side, and are supplied as follows: NDC 46708-437-30 bottles of 30 tablets NDC 46708-437-60 bottles of 60 tablets NDC 46708-437-31 bottles of 100 tablets NDC 46708-437-71 bottles of 500 tablets Store at 25°C (77°F); excursions permitted to 15 to 30°C (59 to 86°F). [see USP Controlled Room Temperature]. Protect from light.