The described invention provides a flowable sustained release microparticulate composition, a kit for treating at least one cerebral artery in a subarachnoid space at risk of interruption due to a brain injury, a method of preparing the composition, and a method for treating an interruption of a cerebral artery in a subarachnoid space at risk of interruption caused by brain injury in a mammal, which reduces signs or symptoms of at least one delayed complication associated with brain injury.