Advances in thrombolytics for treatment of acute ischemic stroke.

Over the past 50 years, thrombolytic agents have been devised with the aim of recanalizing occluded coronary vessels, and later on, applied in the setting of acute ischemic stroke. Pharmacologic agents have generally targeted the plasminogen-plasmin transformation, facilitating the natural process of fibrinolysis. Newer agents with varying degrees of fibrin selectivity and pharmacologic half-life have influenced both recanalization rates and hemorrhagic complications, inside and outside the CNS. Intra-arterial (IA) administration of fibrinolytic agents increases delivery of the drug to the thrombus at a higher concentration with smaller quantities and therefore lowers systemic exposure. Mechanical thrombus disruption or extraction allows for drug delivery to a greater surface area of the thrombus. Delays associated with IA therapy may worsen the risk/benefit ratio of thrombolysis; therefore, combinations of IA-IV treatments have been studied. To date, there are no direct comparative trials to show that endovascular administration is more efficacious or carries a lower risk of hemorrhagic complications than IV tissue plasminogen activator.