Can calcium antagonists affect the hemostatic mechanism and promote rebleeding? An experimental study

Calcium antagonists are currently under investigation as potential beneficial drugs in the prevention of cerebral vasospasm. However, some calcium antagonists have the propensity to inhibit platelet aggregation. This study investigated the danger posed by the administration of calcium antagonists for recurrent hemorrhage in a simulated rat model of subarachnoid hemorrhage. We found that verapamil, a calcium antagonist with antiplatelet activity, lowers clot resistance and may promote rebleeding.