Leflunomide

5 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 these therapies; in some cases, patients had a prior history of a significant hematologic abnormality. Patients taking leflunomide should have platelet, white blood cell count and hemoglobin or hematocrit monitored at baseline and monthly for six months following initiation of therapy and every 6 to 8 weeks thereafter. If used with concomitant methotrexate and/or other potential immunosuppressive agents, chronic monitoring should be monthly. If evidence of bone marrow suppression occurs in a patient taking leflunomide, stop treatment with leflunomide, and perform an accelerated drug elimination procedure to reduce the plasma concentration of the leflunomide active metabolite, teriflunomide [see Warnings and Precautions (5.3) ]. In any situation in which the decision is made to switch from leflunomide to another anti-rheumatic 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. 5.5 Stevens-Johnson Syndrome, Toxic Epidermal Necrolysis, and Drug Reactions with Eosinophilia and Systemic Symptoms Rare cases of Stevens-Johnson syndrome and toxic epidermal necrolysis, and drug reaction with eosinophilia and systemic symptoms (DRESS) have been reported in patients receiving leflunomide. If a patient taking leflunomide develops any of these conditions, stop leflunomide treatment and perform an accelerated drug elimination procedure [see Warnings and Precautions (5.3) ]. 5.6 Malignancy and Lymphoproliferative Disorder The risk of malignancy, particularly lymphoproliferative disorders, is increased with the use of some immunosuppression medications. There is a potential for immunosuppression with leflunomide. No apparent increase in the incidence of malignancies and lymphoproliferative disorders was reported in the clinical trials of leflunomide, but larger dosages and longer-term studies would be needed to determine whether there is an increased risk of malignancy or lymphoproliferative disorders with leflunomide. 5.7 Peripheral Neuropathy Cases of peripheral neuropathy have been reported in patients receiving leflunomide and in clinical studies with teriflunomide, the active metabolite of leflunomide. Most patients recovered after discontinuation of treatment, but some patients had persistent symptoms. Age older than 60 years, concomitant neurotoxic medications, and diabetes may increase the risk for peripheral neuropathy. If a patient taking leflunomide develops a peripheral neuropathy, consider discontinuing leflunomide therapy and performing an accelerated drug elimination procedure [see Dosage and Administration ( 5.3 )]. 5.8 Interstitial Lung Disease Interstitial lung disease and worsening of pre-existing interstitial lung disease have been reported during treatment with leflunomide and has been associated with fatal outcomes [see Adverse Reactions (6.2) ]. The risk of leflunomide -associated interstitial lung disease is increased in patients with a history of interstitial lung disease. Interstitial lung disease is a potentially fatal disorder that may occur acutely at any time during therapy and has 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 leflunomide therapy and for further investigation as appropriate. If discontinuation of leflunomide is necessary, consider performing an accelerated drug elimination procedure [see Warnings and Precautions (5.3) ]. 5.9 Vaccinations No clinical data are available on the efficacy and safety of vaccinations during leflunomide treatment. Vaccination with live vaccines is, however, not recommended. The long half-life of the active metabolite of leflunomide should be considered when contemplating administration of a live vaccine after stopping leflunomide. 5.10 Blood Pressure Monitoring In placebo-controlled studies with the active metabolite of leflunomide, teriflunomide, elevations in blood pressure were observed in some subjects. Blood pressure should be checked before starting treatment with leflunomide and monitored periodically thereafter [See Adverse Reactions (6.1) ].