The Effect of Rifampin on the Metabolism of Istradefylline in Healthy Volunteers.

Inclusion Criteria: * Healthy non-smoking male and post-menopausal female subjects * Body Mass Index: 18.0-35.0 kg/m2, inclusive * Subjects must not be taking drugs that are moderate to potent inhibitors of CYP3A4 or CYP1A2. * Subjects without clinically significant medical history in the judgment of the investigator * Subjects without clinically significant laboratory or ECG abnormalities Exclusion Criteria: * Females that are pregnant or lactating * Administration of an investigational drug within 30 days or 5 elimination half-lives of such investigational drug, whichever is longer, prior to study drug administration, or planned administration of another investigational product or procedure during the subject's participation in this study; * Known history of treatment for drug or alcohol addiction within the previous 12 months; * Subjects with an average alcohol intake of more than 2 units per day or 14 units per week up to 48 hours prior to the istradefylline dose on Day 1. One unit of alcohol is ½ pint of beer (285 mL) or 1 glass of spirits (25 mL) or 1 glass of wine (125 mL); * Donated or lost \> 500 mL of blood within 3 months prior to istradefylline dose on Day 1 of Period 1; * Positive test results for human immunodeficiency virus (HIV) or Hepatitis B surface antigen, or Hepatitis C; * Positive test results for drugs of abuse at screening; * Unable, or unwilling to tolerate multiple venipunctures; * Difficulty fasting or eating the standard meals that will be provided; * Use of tobacco or nicotine-containing products within 90 days of the study start to the Follow-up visit