5.1 Hepatotoxicity

Severe liver injury including fatal liver failure and dysfunction has been reported in some patients treated with leflunomide, which is indicated for rheumatoid arthritis. A similar risk would be expected for teriflunomide because recommended doses of teriflunomide and leflunomide result in a similar range of plasma concentrations of teriflunomide. Patients with pre-existing liver disease may be at increased risk of developing elevated serum transaminases when taking teriflunomide tablets. Patients with pre-existing acute or chronic liver disease, or those with serum alanine aminotransferase (ALT) greater than two times the upper limit of normal (ULN) before initiating treatment, should not normally be treated with teriflunomide tablets. Teriflunomide tablets are contraindicated in patients with severe hepatic impairment [see Contraindications (4)].

In placebo-controlled trials, ALT greater than three times the ULN occurred in 61/1045 (5.8%) and 62/1002 (6.2%) of patients receiving teriflunomide tablets 7 mg and 14 mg, respectively, and 38/997 (3.8%) of patients receiving placebo, during the treatment period. These elevations occurred mostly within the first year of treatment. Half of the cases returned to normal without drug discontinuation. In clinical trials, if ALT elevation was greater than three times the ULN on two consecutive tests, teriflunomide tablets were discontinued and patients underwent an accelerated elimination procedure [see Warnings and Precautions (5.3)]. Of the patients who underwent discontinuation and accelerated elimination in controlled trials, half returned to normal or near normal values within 2 months.

One patient in the controlled trials developed ALT 32 times the ULN and jaundice 5 months after initiation of teriflunomide tablets 14 mg treatment. The patient was hospitalized for 5 weeks and recovered after plasmapheresis and cholestyramine accelerated elimination procedure.

Teriflunomide-induced liver injury in this patient could not be ruled out.

Obtain serum transaminase and bilirubin levels within 6 months before initiation of teriflunomide tablet therapy. Monitor ALT levels at least monthly for six months after starting teriflunomide tablets. Consider additional monitoring when teriflunomide tablets are given with other potentially hepatotoxic drugs.

Consider discontinuing teriflunomide tablets if serum transaminase increase (greater than three times the ULN) is confirmed. Monitor serum transaminase and bilirubin on teriflunomide tablet therapy, particularly in patients who develop symptoms suggestive of hepatic dysfunction, such as unexplained nausea, vomiting, abdominal pain, fatigue, anorexia, or jaundice and/or dark urine. If liver injury is suspected to be teriflunomide-induced, discontinue teriflunomide tablets and start an accelerated elimination procedure [see Warnings and Precautions (5.3)] and monitor liver tests weekly until normalized. If teriflunomide-induced liver injury is unlikely because some other probable cause has been found, resumption of teriflunomide tablet therapy may be considered.

5.2 Embryofetal Toxicity

Teriflunomide may cause fetal harm when administered to a pregnant woman. Teratogenicity and embryofetal lethality occurred in animal reproduction studies in multiple animal species at plasma teriflunomide exposures similar to or lower than that in humans at the maximum recommended human dose (MRHD) of 14 mg/day [see Use in Specific Populations (8.1)].

Teriflunomide tablets are contraindicated for use in pregnant women and in females of reproductive potential not using effective contraception [see Contraindications (4)]. Exclude pregnancy before starting treatment with teriflunomide tablets in females of reproductive potential [see Dosage and Administration (2)]. Advise females of reproductive potential to use effective contraception during teriflunomide tablets treatment and during an accelerated drug elimination procedure after teriflunomide tablets treatment [see Use in Specific Populations (8.3)]. If a woman becomes pregnant while taking teriflunomide tablets, stop treatment with teriflunomide tablets, apprise the patient of the potential risk to a fetus, and perform an accelerated drug elimination procedure to achieve a plasma teriflunomide concentration of less than 0.02 mg/L [see Warnings and Precautions (5.3)].

Upon discontinuing teriflunomide tablets, it is recommended that all females of reproductive potential undergo an accelerated drug elimination procedure. Women receiving teriflunomide tablets treatment who wish to become pregnant must discontinue teriflunomide tablets and undergo an accelerated drug elimination procedure, which includes verification that plasma concentrations of teriflunomide are less than 0.02 mg/L (0.02 mcg/mL). Men wishing to father a child should also discontinue use of teriflunomide tablets and either undergo an accelerated elimination procedure or wait until verification that the plasma teriflunomide concentration is less than 0.02 mg/L (0.02 mcg/mL) [see Use in Specific Population (8.3)]. 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 embryofetal risk [see Contraindications (4), Warnings and Precautions (5.3), and Use in Specific Populations (8.1)].

5.3 Procedure for Accelerated Elimination of Teriflunomide

Teriflunomide is eliminated slowly from the plasma [see Clinical Pharmacology (12.3)]. Without an accelerated elimination procedure, it takes on average 8 months to reach plasma concentrations less than 0.02 mg/L, although because of individual variations in drug clearance it may take as long as 2 years. An accelerated elimination procedure could be used at any time after discontinuation of teriflunomide tablets. Elimination can be accelerated by either of the following procedures:

• Administration of cholestyramine 8 g every 8 hours for 11 days. If cholestyramine 8 g three times a day is not well tolerated, cholestyramine 4 g three times a day can be used.
• Administration of 50 g oral activated charcoal powder every 12 hours for 11 days.

If either elimination procedure is poorly tolerated, treatment days do not need to be consecutive unless there is a need to lower teriflunomide plasma concentration rapidly.

At the end of 11 days, both regimens successfully accelerated teriflunomide elimination, leading to more than 98% decrease in teriflunomide plasma concentrations.

Use of the accelerated elimination procedure may potentially result in return of disease activity if the patient had been responding to teriflunomide tablet treatment.

5.4 Bone Marrow Effects/Immunosuppression Potential/Infections

Bone Marrow Effects

A mean decrease compared to baseline in white blood cell (WBC) count of approximately 15% (mainly neutrophils and lymphocytes) and in platelet count of approximately 10% was observed in placebo-controlled trials with 7 mg and 14 mg of teriflunomide tablets. The decrease in mean WBC count occurred during the first 6 weeks and WBC count remained low during treatment. In placebo-controlled studies, neutrophil count < 1.5 x 109/L was observed in 12% and 16% of patients receiving teriflunomide tablets 7 mg and 14 mg, respectively, compared with 7% of patients receiving placebo; lymphocyte count < 0.8 x 109/L was observed in 10% and 12% of patients receiving teriflunomide tablets 7 mg and 14 mg, respectively, compared with 6% of patients receiving placebo. No cases of serious pancytopenia were reported in premarketing clinical trials of teriflunomide tablets but rare cases of pancytopenia and agranulocytosis have been reported in the postmarketing setting with leflunomide. A similar risk would be expected for teriflunomide tablets [see Clinical Pharmacology (12.3)].  Cases of thrombocytopenia with teriflunomide tablets, including rare cases with platelet counts less than 50,000/mm3, have been reported in the postmarketing setting. Obtain a complete blood cell count (CBC) within 6 months before the initiation of treatment with teriflunomide tablets. Further monitoring should be based on signs and symptoms suggestive of bone marrow suppression.

Risk of Infection/Tuberculosis Screening

Patients with active acute or chronic infections should not start treatment until the infection(s) is resolved. If a patient develops a serious infection consider suspending treatment with teriflunomide tablets and using an accelerated elimination procedure. Reassess the benefits and risks prior to resumption of therapy. Instruct patients receiving teriflunomide tablets to report symptoms of infections to a physician.

Teriflunomide tablets are not recommended for patients with severe immunodeficiency, bone marrow disease, or severe, uncontrolled infections. Medications like teriflunomide tablets that have immunosuppression potential may cause patients to be more susceptible to infections, including opportunistic infections.

In placebo-controlled studies of teriflunomide tablets, no overall increase in the risk of serious infections was observed with teriflunomide tablets 7 mg (2.2%) or 14 mg (2.7%) compared to placebo (2.2%).

However, one fatal case of klebsiella pneumonia sepsis occurred in a patient taking teriflunomide tablets 14 mg for 1.7 years. Fatal infections have been reported in the postmarketing setting in patients receiving leflunomide, especially Pneumocystis jirovecii pneumonia and aspergillosis. Most of the reports were confounded by concomitant immunosuppressant therapy and/or comorbid illness which, in addition to rheumatoid disease, may predispose patients to infection. In clinical studies with teriflunomide tablets, cytomegalovirus hepatitis reactivation has been observed.

In clinical studies with teriflunomide tablets, cases of tuberculosis have been observed. Prior to initiating teriflunomide tablets, screen patients for latent tuberculosis infection with a tuberculin skin test or with a blood test for mycobacterium tuberculosis infection. Teriflunomide tablets have not been studied in patients with a positive tuberculosis screen, and the safety of teriflunomide tablets in individuals with latent tuberculosis infection is unknown. For patients testing positive in tuberculosis screening, treat by standard medical practice prior to therapy with teriflunomide tablets.

Vaccination

No clinical data are available on the efficacy and safety of live vaccinations in patients taking teriflunomide tablets. Vaccination with live vaccines is not recommended. The long half-life of teriflunomide tablets should be considered when contemplating administration of a live vaccine after stopping teriflunomide tablets.

Malignancy

The risk of malignancy, particularly lymphoproliferative disorders, is increased with the use of some immunosuppressive medications. There is a potential for immunosuppression with teriflunomide tablets. No apparent increase in the incidence of malignancies and lymphoproliferative disorders was reported in the teriflunomide tablets clinical trials, but larger and longer-term studies would be needed to determine whether there is an increased risk of malignancy or lymphoproliferative disorders with teriflunomide tablets.

5.5 Hypersensitivity and Serious Skin Reactions

Teriflunomide tablets can cause anaphylaxis and severe allergic reactions [see Contraindications (4)]. Signs and symptoms have included dyspnea, urticaria, and angioedema including lips, eyes, throat, and tongue.

Cases of serious skin reactions, including cases of Stevens-Johnson syndrome (SJS) and a fatal case of toxic epidermal necrolysis (TEN), have been reported with teriflunomide tablets.

In patients treated with leflunomide, the parent compound, very rare cases of Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) have also been reported.

Inform patients of the signs and symptoms of anaphylaxis and angioedema and signs and symptoms that may signal a serious skin reaction. Inform patients that a fever associated with signs of other organ system involvement (e.g., rash, lymphadenopathy, or hepatic dysfunction) may be drug-related.  Instruct patients to discontinue teriflunomide tablets and seek immediate medical care should these signs and symptoms occur. Discontinue teriflunomide tablets, unless the reactions are clearly not drug-related, and begin an accelerated elimination procedure immediately [see Warnings and Precautions (5.3)].  In such cases, patients should not be re-exposed to teriflunomide [see Contraindications (4)].

5.6 Peripheral Neuropathy

In placebo-controlled studies, peripheral neuropathy, including both polyneuropathy and mononeuropathy (e.g., carpal tunnel syndrome), occurred more frequently in patients taking teriflunomide tablets than in patients taking placebo. The incidence of peripheral neuropathy confirmed by nerve conduction studies was 1.4% (13 patients) and 1.9% (17 patients) of patients receiving 7 mg and 14 mg of teriflunomide tablets, respectively, compared with 0.4% receiving placebo (4 patients). Treatment was discontinued in 0.7% (8 patients) with confirmed peripheral neuropathy (3 patients receiving teriflunomide tablets 7 mg and 5 patients receiving teriflunomide tablets 14 mg). Five of them recovered following treatment discontinuation. Not all cases of peripheral neuropathy resolved with continued treatment. Peripheral neuropathy also occurred in patients receiving leflunomide.

Age older than 60 years, concomitant neurotoxic medications, and diabetes may increase the risk for peripheral neuropathy. If a patient taking teriflunomide tablets develops symptoms consistent with peripheral neuropathy, such as bilateral numbness or tingling of hands or feet, consider discontinuing teriflunomide tablet therapy and performing an accelerated elimination procedure [see Warnings and Precautions (5.3)].

5.7 Increased Blood Pressure

In placebo-controlled studies, the mean change from baseline to the end of study in systolic blood pressure was +2.3 mmHg and +2.7 mmHg for teriflunomide tablets 7 mg and 14 mg, respectively, and -0.6 mmHg for placebo. The change from baseline in diastolic blood pressure was +1.4 mmHg and +1.9 mmHg for teriflunomide tablets 7 mg and 14 mg, respectively, and -0.3 mmHg for placebo. Hypertension was an adverse reaction in 3.1% and 4.3% of patients treated with 7 mg or 14 mg of teriflunomide tablets compared with 1.8% for placebo. Check blood pressure before start of teriflunomide tablets treatment and periodically thereafter. Elevated blood pressure should be appropriately managed during treatment with teriflunomide tablets.

5.8 Respiratory Effects

Interstitial lung disease, including acute interstitial pneumonitis, has been reported with teriflunomide tablets in the postmarketing setting.

Interstitial lung disease and worsening of pre-existing interstitial lung disease have been reported during treatment with leflunomide. Interstitial lung disease may be fatal and may occur acutely at any time during therapy with a variable clinical presentation. New onset or worsening pulmonary symptoms, such as cough and dyspnea, with or without associated fever, may be a reason for discontinuation of therapy and for further investigation as appropriate. If discontinuation of the drug is necessary, consider initiation of an accelerated elimination procedure [see Warnings and Precautions (5.3)].

5.9 Concomitant Use with Immunosuppressive or Immunomodulating Therapies

Co-administration with antineoplastic or immunosuppressive therapies used for treatment of multiple sclerosis has not been evaluated. Safety studies in which teriflunomide tablets were concomitantly administered with other immune modulating therapies for up to one year (interferon beta, glatiramer acetate) did not reveal any specific safety concerns. The long term safety of these combinations in the treatment of multiple sclerosis has not been established.

In any situation in which the decision is made to switch from teriflunomide tablets to another agent with a known potential for hematologic suppression, it would be prudent to monitor for hematologic toxicity, because there will be overlap of systemic exposure to both compounds. Use of an accelerated elimination procedure may decrease this risk, but may also potentially result in return of disease activity if the patient had been responding to teriflunomide tablet treatment [see Warnings and Precautions (5.3)].

6.1 Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice.

A total of 2047 patients receiving teriflunomide tablets (7 mg or 14 mg once daily) constituted the safety population in the pooled analysis of placebo controlled studies in patients with relapsing forms of multiple sclerosis; of these, 71% were female. The average age was 37 years.

Table 1 lists adverse reactions in placebo-controlled trials with rates that were at least 2% for teriflunomide tablets patients and also at least 2% above the rate in placebo patients. The most common were headache, an increase in ALT, diarrhea, alopecia, and nausea.  The adverse reaction most commonly associated with discontinuation was an increase in ALT (3.3%, 2.6%, and 2.3% of all patients in the teriflunomide tablets 7 mg, teriflunomide tablets 14 mg, and placebo treatment arms, respectively).

Table 1:   Adverse Reactions in Pooled Placebo-Controlled Studies in Patients with Relapsing Forms of Multiple Sclerosis

Cardiovascular Deaths

Four cardiovascular deaths, including three sudden deaths, and one myocardial infarction in a patient with a history of hyperlipidemia and hypertension were reported among approximately 2600 patients exposed to teriflunomide tablets in the premarketing database. These cardiovascular deaths occurred during uncontrolled extension studies, one to nine years after initiation of treatment. A relationship between teriflunomide tablets and cardiovascular death has not been established.

Acute Renal Failure

In placebo-controlled studies, creatinine values increased more than 100% over baseline in 8/1045 (0.8%) patients in the 7 mg teriflunomide tablets group and 6/1002 (0.6%) patients in the 14 mg teriflunomide tablets group versus 4/997 (0.4%) patients in the placebo group. These elevations were transient. Some elevations were accompanied by hyperkalemia. Teriflunomide tablets may cause acute uric acid nephropathy with transient acute renal failure because teriflunomide tablets increases renal uric acid clearance.

Hypophosphatemia

In clinical trials, 18% of teriflunomide tablet-treated patients had hypophosphatemia with serum phosphorus levels of at least 0.6 mmol/L, compared to 7% of placebo-treated patients; 4% of teriflunomide tablet-treated patients had hypophosphatemia with serum phosphorus levels at least 0.3 mmol/L but less than 0.6 mmol/L, compared to 0.8% of placebo-treated patients. No patient in any treatment group had a serum phosphorus below 0.3 mmol/L.

6.2 Postmarketing Experience

The following adverse reactions have been identified during postapproval use of teriflunomide tablets. 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.

• Hypersensitivity reactions, some of which were severe, such as anaphylaxis and angioedema [see Warnings and Precautions (5.5)]
• Severe skin reactions, including toxic epidermal necrolysis and Stevens-Johnson syndrome [see Warnings and Precautions (5.5)]
• Psoriasis or worsening of psoriasis (including pustular psoriasis)
• Thrombocytopenia [see Warnings and Precautions (5.4)]
• Interstitial lung disease [see Warnings and Precautions (5.8)]
• Pancreatitis

8.1 Pregnancy

Pregnancy Exposure Registry

There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to teriflunomide during pregnancy. Healthcare providers and patients are encouraged to report pregnancies by calling 1-877-311-8972.

Risk Summary

Teriflunomide tablets are contraindicated for use in pregnant women and females of reproductive potential not using effective contraception because of the potential for fetal harm based on animal data [see Contraindications (4) and Warnings and Precautions (5.2)].

In animal reproduction studies in rat and rabbit, oral administration of teriflunomide during organogenesis caused teratogenicity and embryolethality at plasma exposures (AUC) lower than that at the maximum recommended human dose (MRHD) of 14 mg/day [see Data]. Available human data from pregnancy registries, clinical trials, pharmacovigilance cases, and published literature are too limited to draw any conclusions, but they do not clearly indicate increased birth defects or miscarriage associated with inadvertent teriflunomide exposure in the early first trimester when followed by an accelerated elimination procedure [see Clinical Considerations and Data]. There are no human data pertaining to exposures later in the first trimester or beyond.

In the US general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. The background risk of major birth defects and miscarriage in the indicated population is unknown.

Clinical Considerations

Fetal/Neonatal adverse reactions

Lowering the plasma concentration of teriflunomide by instituting an accelerated drug elimination procedure as soon as pregnancy is detected may decrease the risk to the fetus from teriflunomide tablets. 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

Human data

Available human data are limited. Prospectively reported data (from clinical trials and postmarketing reports) from > 150 pregnancies in patients treated with teriflunomide tablets and > 300 pregnancies in patients treated with leflunomide have not demonstrated an increased rate of congenital malformations or miscarriage following teriflunomide exposure in the early first trimester when followed by an accelerated elimination procedure. Specific patterns of major congenital malformations in humans have not been observed. Limitations of these data include an inadequate number of reported pregnancies from which to draw conclusions, the short duration of drug exposure in reported pregnancies, which precludes a full evaluation of the fetal risks, incomplete reporting, and the inability to control for confounders (such as underlying maternal disease and use of concomitant medications).

Animal data

When teriflunomide (oral doses of 1, 3, or 10 mg/kg/day) was administered to pregnant rats throughout the period of organogenesis, high incidences of fetal malformation (primarily craniofacial, and axial and appendicular skeletal defects) and fetal death were observed at doses not associated with maternal toxicity. Adverse effects on fetal development were observed following dosing at various stages throughout organogenesis. Maternal plasma exposure at the no-effect level (1.0 mg/kg/day) for fetal developmental toxicity in rats was less than that in humans at the maximum recommended human dose (MRHD, 14 mg/day).

Administration of teriflunomide (oral doses of 1, 3.5, or 12 mg/kg/day) to pregnant rabbits throughout organogenesis resulted in high incidences of fetal malformation (primarily craniofacial, and axial and appendicular skeletal defects) and fetal death at doses associated with minimal maternal toxicity. Maternal plasma exposure at the no-effect dose (1.0 mg/kg/day) for fetal developmental toxicity in rabbits was less than that in humans at the MRHD.

In studies in which teriflunomide (oral doses of 0.05, 0.1, 0.3, 0.6, or 1.0 mg/kg/day) was administered to rats during gestation and lactation, decreased growth, eye and skin abnormalities, and high incidences of malformation (limb defects) and postnatal death were observed in the offspring at doses not associated with maternal toxicity. Maternal plasma exposure at the no-effect dose for prenatal and postnatal developmental toxicity in rats (0.10 mg/kg/day) was less than that in humans at the MRHD.

In animal reproduction studies of leflunomide, embryolethality and teratogenic effects were observed in pregnant rat and rabbit at or below clinically relevant plasma teriflunomide exposures (AUC). In published reproduction studies in pregnant mice, leflunomide was embryolethal and increased the incidence of malformations (craniofacial, axial skeletal, heart and great vessel). Supplementation with exogenous uridine reduced the teratogenic effects in pregnant mice, suggesting that the mode of action (inhibition of mitochondrial enzyme dihydroorotate dehydrogenase) is the same for therapeutic efficacy and developmental toxicity.

At recommended doses in humans, teriflunomide and leflunomide result in a similar range of plasma concentrations of teriflunomide.

8.2 Lactation

Risk Summary

There are no data on the presence of teriflunomide in human milk, the effects on the breastfed infant, or the effects on milk production. Teriflunomide was detected in rat milk following a single oral dose. Because of the potential for adverse reactions in a breastfed infant from teriflunomide, women should not breastfeed during treatment with teriflunomide tablets.

8.3 Females and Males of Reproductive Potential

Pregnancy Testing

Exclude pregnancy prior to initiation of treatment with teriflunomide tablets in females of reproductive potential. Advise females to notify their healthcare provider immediately if pregnancy occurs or is suspected during treatment [see Warnings and Precautions (5.2, 5.3) and Use in Specific Populations (8.1)].

Contraception

Females

Females of reproductive potential should use effective contraception while taking teriflunomide tablets. If teriflunomide tablets are discontinued, use of contraception should be continued until it is verified that plasma concentrations of teriflunomide are less than 0.02 mg/L (0.02 mcg/mL, the level expected to have minimal fetal risk, based on animal data).

Females of reproductive potential who wish to become pregnant should discontinue teriflunomide tablets and undergo an accelerated elimination procedure. Effective contraception should be used until it is verified that plasma concentrations of teriflunomide are less than 0.02 mg/L (0.02 mcg/mL) [see Warnings and Precautions (5.2, 5.3) and Use in Specific Populations (8.1)].

Males

Teriflunomide is detected in human semen. Animal studies to specifically evaluate the risk of male mediated fetal toxicity have not been conducted. To minimize any possible risk, men not wishing to father a child and their female partners should use effective contraception. Men wishing to father a child should discontinue use of teriflunomide tablets and either undergo an accelerated elimination procedure or wait until verification that the plasma teriflunomide concentration is less than 0.02 mg/L (0.02 mcg/mL) [see Warnings and Precautions (5.3)].

8.4 Pediatric Use

Safety and effectiveness in pediatric patients have not been established.

8.5 Geriatric Use

Clinical studies of teriflunomide tablets did not include patients over 65 years old.

8.6 Hepatic Impairment

No dosage adjustment is necessary for patients with mild and moderate hepatic impairment. The pharmacokinetics of teriflunomide in severe hepatic impairment has not been evaluated.

Teriflunomide tablets are contraindicated in patients with severe hepatic impairment [see Contraindications (4), Warnings and Precautions (5.1), and Clinical Pharmacology (12.3)].

8.7 Renal Impairment

No dosage adjustment is necessary for patients with mild, moderate, and severe renal impairment [see Clinical Pharmacology (12.3)].

12.1 Mechanism of Action

Teriflunomide, an immunomodulatory agent with anti-inflammatory properties, inhibits dihydroorotate dehydrogenase, a mitochondrial enzyme involved in de novo pyrimidine synthesis. The exact mechanism by which teriflunomide exerts its therapeutic effect in multiple sclerosis is unknown but may involve a reduction in the number of activated lymphocytes in CNS.

12.2 Pharmacodynamics

Potential to Prolong the QT Interval

In a placebo controlled thorough QT study performed in healthy subjects, there was no evidence that teriflunomide caused QT interval prolongation of clinical significance (i.e. the upper bound of the 90% confidence interval for the largest placebo-adjusted, baseline-corrected QTc was below 10 ms).

12.3 Pharmacokinetics

Teriflunomide is the principal active metabolite of leflunomide and is responsible for leflunomide’s activity in vivo. At recommended doses, teriflunomide and leflunomide result in a similar range of plasma concentrations of teriflunomide.

Based on a population analysis of teriflunomide in healthy volunteers and MS patients, median t1/2 was approximately 18 and 19 days after repeated doses of 7 mg and 14 mg respectively. It takes approximately 3 months respectively to reach steady-state concentrations. The estimated AUC accumulation ratio is approximately 30 after repeated doses of 7 or 14 mg.

Absorption

Median time to reach maximum plasma concentrations is between 1 to 4 hours post dose following oral administration of teriflunomide.

Food does not have a clinically relevant effect on teriflunomide pharmacokinetics.

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.

Metabolism

Teriflunomide is the major circulating moiety detected in plasma. The primary biotransformation pathway to minor metabolites of teriflunomide is hydrolysis, with oxidation being a minor pathway. Secondary pathways involve oxidation, N-acetylation and sulfate conjugation.

Elimination

Teriflunomide is eliminated mainly through 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). After a single IV administration, the total body clearance of teriflunomide is 30.5 mL/h.

Drug Interaction Studies

Teriflunomide is not metabolized by Cytochrome P450 or flavin monoamine oxidase enzymes.

The potential effect of teriflunomide tablets on other drugs

CYP2C8 substrates

There was an increase in mean repaglinide Cmax 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 Cmax and AUC of caffeine by 18% and 55%, respectively, suggesting that teriflunomide may be a weak inducer of CYP1A2 in vivo [see Drug Interactions (7)].

OAT3 substrates

There was an increase in mean cefaclor Cmax 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 Cmax 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 Cmax and AUC0-24 (1.58- and 1.54-fold, respectively) and levonorgestrel Cmax and AUC0-24 (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).

The potential effect of other drugs on teriflunomide tablets

Potent CYP and transporter inducers: Rifampin did not affect the pharmacokinetics of teriflunomide.

Specific Populations

Hepatic impairment

Mild and moderate hepatic impairment had no impact on the pharmacokinetics of teriflunomide. The pharmacokinetics of teriflunomide in severe hepatic impairment has not been evaluated [see Contraindications (4), Warnings and Precautions (5.1), and Use in Specific Populations (8.6)].

Renal impairment

Severe renal impairment had no impact on the pharmacokinetics of teriflunomide [see Use in Specific Populations (8.7)].

Gender

In a population analysis, the clearance rate for teriflunomide is 23% less in females than in males.

Race

Effect of race on the pharmacokinetics of teriflunomide cannot be adequately assessed due to a low number of non-white patients in the clinical trials.

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

Carcinogenesis

No evidence of carcinogenicity was observed in lifetime carcinogenicity bioassays in mouse and rat. In mouse, teriflunomide was administered orally at doses up to 12 mg/kg/day for up to 95 to 104 weeks; plasma teriflunomide exposures (AUC) at the highest dose tested are approximately 3 times that in humans at the maximum recommended human dose (MRHD, 14 mg/day). In rat, teriflunomide was administered orally at doses up to 4 mg/kg/day for up to 97 to 104 weeks; plasma teriflunomide AUCs at the highest doses tested are less than that in humans at the MRHD.

Mutagenesis

Teriflunomide was negative in the in vitro bacterial reverse mutation (Ames) assay, the in vitro HPRT assay, and in in vivo micronucleus and chromosomal aberration assays. Teriflunomide was positive in an in vitro chromosomal aberration assay in human lymphocytes, with and without metabolic activation. Addition of uridine (to supplement the pyrimidine pool) reduced the magnitude of the clastogenic effect; however, teriflunomide was positive in the in vitro chromosomal aberration assay, even in the presence of uridine.

4-Trifluoromethylaniline (4-TFMA), a minor metabolite of teriflunomide, was positive in the in vitro bacterial reverse mutation (Ames) assay, the in vitro HPRT assay, and the in vitro chromosomal aberration assay in mammalian cells. 4-TFMA was negative in in vivo micronucleus and chromosomal aberration assays.

Impairment of Fertility

Oral administration of teriflunomide (0, 1, 3, 10 mg/kg/day) to male rats prior to and during mating (to untreated females) resulted in no adverse effects on fertility; however, reduced epididymal sperm count was observed at the mid and high doses tested. The no-effect dose for reproductive toxicity in male rats (1 mg/kg) is less than the MRHD on a mg/m2 basis.

Oral administration of teriflunomide (0, 0.84, 2.6, 8.6 mg/kg/day) to female rats, prior to and during mating (to untreated males) and continuing to gestation day 6, resulted in embryolethality, reduced fetal body weight, and/or malformations at all doses tested. Due to marked embryolethality at the highest dose tested, no fetuses were available for evaluation. The lowest dose tested is less than the MRHD on a mg/m2 basis.