Evaluation of the Efficacy and Safety of Clazosentan in Reversing Cerebral Vasospasm in Adult Subjects With Aneurysmal Subarachnoid Hemorrhage

Inclusion Criteria: * Signed informed consent from the subject or proxy/legal representative * Aneurysmal subarachnoid hemorrhage (aSAH)confirmed by digital subtraction angiogram (DSA) or computed tomography angiogram (CTA), successfully secured by surgical clipping or endovascular coiling within 72 hours of rupture * World Federation of Neurological Surgeons (WFNS) grade 1-4 at admission, and which must not increase to grade 5 at the time of enrollment * Moderate or severe global cerebral vasospasm at the time of enrollment, documented by digital subtraction angiography (DSA) performed not earlier than 48 hours post aneurysm-securing procedure * Women of childbearing potential must have a negative serum pregnancy test at screening and must use a reliable method of contraception from hospital discharge up to 30 days after discontinuation of study drug infusion, and fertile males must use a condom as a contraceptive method during this same period Exclusion Criteria: * SAH due to causes other than a saccular aneurysm * Any moderate or severe cerebral vasospasm on angiography prior to the aneurysm-securing procedure * Presence of a new or worsened cerebral infarct or evidence of significant bleeding post aneurysm-securing procedure, or re-bleeding, on a CT scan performed within 24 hours prior to enrollment * Total bilirubin \> 2 times the upper limit of normal, and / or a known diagnosis or clinical suspicion of liver cirrhosis or moderate to severe hepatic impairment * Any severe or unstable concomitant condition or disease (e.g., cancer, hematological, or coronary disease) or chronic condition (e.g., drug abuse, severe alcoholism), which, in the opinion of the investigator, would interfere with the assessment of the safety or effect of the study treatment