Desmoteplase is a novel, highly fibrin-specific "clot-busting" (thrombolytic) drug in development that reached phase III clinical trials.

Desmoteplase, a chemical found in the saliva of vampire bats, has the effect of catalysing the conversion of plasminogen to plasmin, which is the enzyme responsible for breaking down fibrin blood clots.

As early as in 1932, the saliva of the vampire bat (Desmodus rotundus) was known to lead to interference with the haemostatic mechanism of the host animal.

As a result, desmoteplase, in comparison to rt-PA, has high fibrin selectivity (100,000- v. 550-fold increase in catalytic activity), an absence of neurotoxicity, and no apparent negative effect on the blood–brain barrier.

This could be explained by the inclusion of a substantial number of patients with a mild stroke at baseline and small mismatch volumes associated with no vessel occlusion.

Patients are selected with occlusion or high-grade stenosis (TIMI 0-1) in proximal cerebral arteries as assessed by magnetic resonance or computed tomography angiography.

Nevertheless, CT-perfusion scans and MRI-perfusion versus MRI-diffusion demonstrate that even after six hours a significant ischaemic penumbra of brain tissue may be salvageable.