Leflunomide Drug Information

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.

Recommended Dosage

The recommended dosage of Leflunomide is 20 mg once daily. Treatment may be initiated with or without a loading dose, depending upon the patient's risk of leflunomide -associated hepatotoxicity and leflunomide associated myelosuppression. The loading dosage provides steady-state concentrations more rapidly.

For patients who are at low risk for leflunomide-associated hepatotoxicity and leflunomide-associated myelosuppression the recommended leflunomide loading dosage is 100 mg once daily for 3 days. Subsequently administer 20 mg once daily. For patients at high risk for leflunomide-associated hepatotoxicity (e.g., those taking concomitant methotrexate) or leflunomide-associated myelosuppression (e.g., patients taking concomitant immunosuppressants), the recommended leflunomide dosage is 20 mg once daily without a loading dose.

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, since the active metabolite of leflunomide, teriflunomide, is slowly eliminated from the plasma. After stopping leflunomide treatment, an accelerated drug elimination procedure is recommended to reduce the plasma concentrations of the active metabolite, teriflunomide.

Without use of an accelerated drug elimination procedure, it may take up to 2 years to reach undetectable plasma teriflunomide concentrations after stopping leflunomide.

Evaluation and Testing

Prior to Starting leflunomide tablets Prior to starting leflunomide treatment the following evaluations and tests are recommended: Evaluate patients for active tuberculosis and screen patients for latent tuberculosis infection Laboratory tests including serum alanine aminotransferase (ALT); and white blood cell, hemoglobin or hematocrit, and platelet counts For females of reproductive potential, pregnancy testing Check blood pressure

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* LEF 20 mg/day (n=182) PL (n=118) MTX 7.5-15 mg/wk (n=182) LEF 20mg/day (n=133) PL (n=92) SSZ 2.0 g/day LEF 20 mg/day (n=501) MTX 7.5-15 mg/wk (n=498) ALT(SGPT)>3-fold ULN (n%) 8 3 5 2 1 2 13 83 Reversed to ≤ 2-fold ULN: 8 3 5 2 1 2 12 82 Timing of Elevation 0 - 3 Months 4 - 6 Months 7 - 9 Months 10 - 12 Months 6 1 1 - 1 1 1 - 1 3 1 - 2 - - - 1 - - - 2 - - - 7 1 - 5 27 34 16 6 LEF = leflunomide, 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 LEF 20 mg/day (N=315) PL (N=210) SSZ 2.0g/day (N=133) MTX 7.5-15 mg/wk (N=182) LEF 20 mg/day (N=501) MTX 7.5–15 mg/wk (N=498) LEF (N=1339) 2 Diarrhea 27% 12% 10% 20% 22% 10% 17% Headache 13% 11% 12% 21% 10% 8% 7% Nausea 13% 11% 19% 18% 13% 18% 9% Rash 12% 7% 11% 9% 11% 10% 10% Abnormal Liver Enzymes 10% 2% 4% 10% 6% 17% 5% Alopecia 9% 1% 6% 6% 17% 10% 10% Hypertension 3 9% 4% 4% 3% 10% 4% 10% Asthenia 6% 4% 5% 6% 3% 3% 3% Back Pain 6% 3% 4% 9% 8% 7% 5% GI/Abdominal Pain 6% 4% 7% 8% 8% 8% 5% Abdominal Pain 5% 4% 4% 8% 6% 4% 6% Allergic Reaction 5% 2% 0% 6% 1% 2% 2% Bronchitis 5% 2% 4% 7% 8% 7% 7% Dizziness 5% 3% 6% 5% 7% 6% 4% Mouth Ulcer 5% 4% 3% 10% 3% 6% 3% Pruritus 5% 2% 3% 2% 6% 2% 4% Rhinitis 5% 2% 4% 3% 2% 2% 2% Vomiting 5% 4% 4% 3% 3% 3% 3% Tenosynovitis 2% 0% 1% 2% 5% 1% 3% LEF = leflunomide, MTX = methotrexate, PL = placebo, SSZ = sulfasalazine 1 Only 10% of patients in Trial3 received folate. All patients in Trial 1 received folate; none in Trial 2 received folate. 2 Includes all controlled and uncontrolled trials with leflunomide (duration up to 12 3 Hypertension as a preexisting condition was overrepresented in all leflunomide treatment groups in phase III trials.

Adverse events during a second year of treatment with leflunomide in clinical trials were consistent with those observed during the first year of treatment and occurred at a similar or lower incidence. Less Common Adverse Reactions In addition, in controlled clinical trials, the following adverse events in the leflunomide treatment group occurred at a higher incidence than in the placebo group. These adverse events were deemed possibly related to the study drug.

Blood and Lymphatic System: leukocytosis, thrombocytopenia; Cardiovascular: chest pain, palpitation, thrombophlebitis of the leg, varicose vein; Eye: blurred vision, eye disorder, papilledema, retinal disorder, retinal hemorrhage; Gastrointestinal: alkaline phosphatase increased, anorexia, bilirubinemia, flatulence, gamma- GT increased, salivary gland enlarged, sore throat, vomiting, dry mouth; General Disorders: malaise; Immune System: anaphylactic reaction; Infection: abscess, flu syndrome, vaginal moniliasis; Nervous System: dizziness, headache, somnolence; Respiratory System: dyspnea;

Post Marketing Experience

The following additional adverse reactions have been identified during postapproval use of leflunomide. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Blood and Lymphatic System: agranulocytosis, leukopenia, neutropenia, pancytopenia; Infection: opportunistic infections, severe infections including sepsis; Gastrointestinal: acute hepatic necrosis, colitis, including microscpic colitis, hepatitis, jaundice/cholestasis, pancreatitis; severe liver injury such as hepatic failure Immune System: angioedema; Nervous system: peripheral neuropathy; Respiratory: interstitial lung disease, including interstitial pneumonitis and pulmonary fibrosis, which may be fatal; pulmonary hypertension; Skin and Appendages: erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis, vasculitis including cutaneous necrotizing vasculitis, cutaneous lupus erythematosus, pustular psoriasis or worsening psoriasis.

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. Effect of potent CYP and transporter inducers Leflunomide is metabolized by CYP450 metabolizing enzymes.

Concomitant use of leflunomide 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 when coadministered with rifampin. Because of the potential for leflunomide concentrations to continue to increase with multiple dosing, caution should be used if patients are to be receiving both leflunomide and rifampin.

Effect on CYP2C8 substrates Teriflunomide is an inhibitor of CYP2C8 in vivo. In patients taking leflunomide, 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.

Effect on warfarin Coadministration of leflunomide with warfarin requires close monitoring of the international normalized ratio (INR) because teriflunomide, the active metabolite of leflunomide, 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 Effect on CYP1A2 substrates Teriflunomide, the active metabolite of leflunomide, may be a weak inducer of CYP1A2 in vivo. In patients taking leflunomide, 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. Effect on organic anion transporter 3 (OAT3) substrates Teriflunomide inhibits the activity of OAT3 in vivo. In patients taking leflunomide, 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. 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, 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. Drugs metabolized by CYP2C8 and OAT3 transporters: Monitor patients because teriflunomide may increase exposure of these drugs. Teriflunomide may increase exposure of ethinylestradiol and levonorgestrel.

Choose an appropriate oral contraceptive. Drugs metabolized by CYP1A2: Monitor patients because teriflunomide may decrease exposure of these drugs. Warfarin: Monitor INR as teriflunomide may decrease INR. Drugs metabolized by BCRP and OATP1B1/B3 transporters: Monitor patients because teriflunomide may increase exposure of these drugs.

Rosuvastatin: The dose of rosuvastatin should not exceed 10 mg once daily in patients taking leflunomide.

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) . 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 to 4% and of miscarriage is 15 to 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). 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.. 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 microophthalmia 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 embryofetal 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 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.

Pediatric Use The safety and effectiveness of leflunomide in pediatric patients have not been established. The safety and effectiveness of leflunomide in the treatment of polyarticular course juvenile idiopathic arthritis (JIA) was evaluated in a single multicenter, double-blind, active-controlled trial in 94 pediatric patients (1:1 randomization) with polyarticular course juvenile idiopathic arthritis (JIA) as defined by the American College of Rheumatology (ACR). In this population, leflunomide treatment was found not to be effective. The safety of leflunomide was studied in 74 patients with polyarticular course JIA ranging in age from 3 to 17 years (47 patients from the active-controlled study and 27 from an open-label safety and pharmacokinetic study). The most common adverse events included abdominal pain, diarrhea, nausea, vomiting, oral ulcers, upper respiratory tract infections, alopecia, rash, headache, and dizziness.

Less common adverse events included anemia, hypertension, and weight loss. Fourteen pediatric patients experienced ALT and/or AST elevations, nine between 1.2 and 3-fold the upper limit of normal, five between 3 and 8-fold the upper limit of normal.

Leflunomide tablets are 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.

Patients with severe hepatic impairment. Patients with known hypersensitivity to leflunomide or any of the other components of leflunomide tablets. Known reactions include anaphylaxis.

Patients being treated with teriflunomide. Pregnancy. Severe hepatic impairment.

Hypersensitivity to leflunomide tablet or any of its inactive components. Current teriflunomide treatment.

There have been reports of chronic overdose in patients taking leflunomide 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. 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. Studies with both hemodialysis and CAPD (chronic ambulatory peritoneal dialysis) indicate that teriflunomide, the primary metabolite of leflunomide, is not dialyzable.