Bioavailability Study of Leflunomide Tablets Under Fasting Conditions

Inclusion Criteria: * All subjects selected for this study will be at least 18 years of age. * Females must be physically unable to become pregnant. * Males must be vasectomized. * Each subject shall be given a general physical examination within 28 days of initiation of the study. * Such examination includes, but is not limited to, blood pressure, general observations, and history. * Each female subject will be given a serum pregnancy test as part of the pre- study screening process * At the end of study, the subject will have an exit evaluation consisting of interim history, global evaluation, clinical laboratory measurements * Adequate blood and urine samples should be obtained within 28 days before beginning of the first period and at the end of the trial for clinical laboratory measurements * Clinical laboratory measurements will include hematology, clinical chemistry, urine analysis, HIV screen, hepatitis-B,C screen, drugs of abuse screen before dosing. Exclusion Criteria: * Subjects with a history of chronic alcohol consumption (during past 2 years), drug addiction,or recent serious gastrointestinal, renal, hepatic or cardiovascular disease, tuberculosis, epilepsy, asthma (during past 5 years), diabetes, psychosis or glaucoma will not be eligible for this study * Subjects whose clinical laboratory test values are greater tahn 20% outside the normal range may be retested.If the clinical values are out side the range on retesting the subject will not be eligible to participate in the study unless the clinical investigator deems the result to not be significant * Subjects who have a history of allergic responses to the class of drug being tested should be excluded from the study.Subjects who have a history of allergic responses to cholestyramine should be excluded from the study. * All subjects will have urine samples assayed for the presence of drugs and abuse as part of the clinical laboratory screening procedures and at check-in before dosing. Subjects found to have urine concentrations of any of the tested drugs will not be allowed to participate. * Subjects should not have donated blood and/or plasma for at least thirty(30) days prior to the first dosing of the study. * Subjects who have taken any investigational drug within thirty(30)days prior to the first dosing of the study will not be allowed to participate. * Female subjects who are pregnant or who are able(women with child bearing potential) to become pregnant during the study will not be allowed to participate. * All female subjects will be screened for pregnancy at check-in. Subjects with positive or inconclusive results will be withdrawn from the study. * Male subjects who are physically able to father a child will not be allowed to participate. Male subjects must be vasectomized(at least 3 months) with medical verification. * Subjects who have taken any product containing leflunomide within 180 days of dosing will not be allowed to participate in this study.