A Study in Healthy Male Subjects to Investigate Whether Administration of Rifampicin Can Affect the Fate of Clazosentan in the Body of Clazosentan

Inclusion Criteria: * Signed informed consent in a language understandable to the subject prior to any study-mandated procedure. * Healthy male subjects aged between 18 and 65 years (inclusive) at Screening. * Body mass index (BMI) of 18.0 to 30.0 kg/m2 (inclusive) at Screening. * Systolic blood pressure (SBP) 100-145 mmHg, diastolic blood pressure (DBP) 50-90 mmHg, and pulse rate 45-90 bpm (inclusive), measured on the same arm, after 5 min in the supine position at Screening and on Day -1 of the first Period. * Healthy on the basis of physical examination, cardiovascular assessments and laboratory tests. Study-specific criteria \- Acceptance for the duration of the study and for 3 months thereafter to use a condom and not to procreate. Exclusion Criteria: * Previous exposure to clazosentan. * Previous exposure to rifampicin within 3 months prior to Screening. * Known hypersensitivity to clazosentan or rifampicin or treatments of the same class, or any of their excipients. * Known hypersensitivity or allergy to natural rubber latex. * Participation in a clinical study involving study treatment administration within 3 months prior to Screening or in more than 4 clinical studies within 1 year prior to Screening. * History or clinical evidence of alcoholism or drug abuse within the 3-year period prior to Screening. * Positive results for hepatitis B surface antigen or hepatitis C virus antibody at Screening. * Positive results from the HIV serology at Screening. * Any circumstances or conditions, which, in the opinion of the investigator, may affect full participation in the study or compliance with the protocol.