The study will investigate whether administration of clazosentan can affect normal heart function in healthy subjects

Inclusion Criteria:

General criteria

• Signed informed consent prior to any study-mandated procedure
• Body mass index of 18.0-30.0 kg/m2 (inclusive) at Screening
• Systolic blood pressure 100-145 mmHg, diastolic blood pressure 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
• 12-lead ECG: QT interval corrected using Fridericia's formula (QTcF) <450 ms for male subjects and < 470 ms for female subjects, QRS interval < 110 ms, PR interval ≤ 200 ms, and heart rate (HR) ≤ 90 bpm without clinically relevant abnormalities using a 12-lead ECG measured after 5 min in the supine position at Screening and on Day -1 of the first Period

Study-specific criteria

• Women of non-childbearing potential
• Male subjects must accept to use a condom and not to procreate for the duration of the study and for 3 months thereafter

Exclusion Criteria:

General criteria

• Previous exposure to clazosentan or to moxifloxacin within 3 months prior to Screening
• Known hypersensitivity to any of clazosentan excipients or to moxifloxacin or any of its excipients
• Any contraindication to moxifloxacin treatment
• Acute, ongoing, recurrent, or chronic systemic disease able to interfere with the evaluation of the study
• Previous history of fainting, collapse, syncope, orthostatic hypotension, or vasovagal reactions if considered clinically significant by the investigator
• Veins unsuitable for i.v. puncture on either arm (e.g., veins that are difficult to locate, access, or puncture, veins with a tendency to rupture during or after puncture)
• 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
• Any circumstances or conditions, which, in the opinion of the investigator, may affect full participation in the study or compliance with the protocol

Study-specific criteria

• History or presence of rhythm disorders (e.g., sinoatrial heart block, sick-sinus syndrome, second- or third-degree atrioventricular block, long QT syndrome, symptomatic bradycardia, atrial flutter, or atrial fibrillation)