Clinical Research Study With Clazosentan to Evaluate Its Effects on Preventing Complications Due to the Narrowing of the Blood Vessels (Vasospasm) in the Brain, Caused by Bleeding Onto the Surface of the Brain

When a blood vessel just outside the brain bursts and causes bleeding onto its surface, the space surrounding the brain (the subarachnoid space) fills with blood. This condition is called subarachnoid hemorrhage. The bleeding due to the rupture of a pouch-like structure or a bulge (called an aneurysm) that formed on one of the blood vessels is condition called aneurysmal subarachnoid hemorrhage (aSAH). In this study, clazosentan is being tested against normal routine medical care to determine if clazosentan can reduce the risk of developing complications related to vasospasm and permanent brain damage. Participation will last for approximately 6 months from the episode of bleeding. For subjects randomized in the high-risk prevention group, treatment will start within 96 hours following the time of the aneurysm rupture, and be administered where possible, for 14 days. For subjects randomized in the early treatment group, treatment must begin within 24 hours of the time of the angiogram documenting the cerebral vasospasm necessary for entry into the study. Treatment will be administered for a minimum of 6 days and a maximum of 14 days. Recruitment in the early treatment group has been discontinued. The end-of-study will be conducted as a telephone interview 6 months after the episode of bleeding.