Intrathecal Administration of Thrombin Inhibitor Ameliorates Cerebral Vasospasm

The role of thrombin as a spasmogen after subarachnoid hemorrhage was evaluated using the intrathecally administered thrombin inhibitor hirudin, released from a drug delivery system (DDS) based on collagen in a canine vasospasm model. The DDS was implanted into the cisterna magna with autologous blood in the hirudin-treated group. The reduction in the angiographical diameter of the basilar artery was only 19% in the hirudin-treated group on day 7, showing a significant difference between hirudin-treated and nontreated groups (p < 0.01). These results suggest that thrombin is an important cause of vasospasm. The collagen DDS has great potential for treatment in the cerebrospinal fluid milieu.