Thrombin is a multifunctional serine protease that plays a primary rol
e in the pathogenic pathway of thrombosis as a consequence of its acti
ons on the two principal components of blood clots, fibrin and activat
ed platelets. Deficiencies in available therapies, heparin and coumadi
n, have recently led to an intense effort in several pharmaceutical co
mpanies to develop potent, selective, and preferably orally bioavailab
le direct thrombin inhibitors. Substantial progress has been made on p
otent and selective compounds and work is ongoing to improve other pha
rmacokinetic properties such as oral bioavailability and duration of a
ction, properties necessary for successful clinical development. (C) C
urrent Biology Ltd ISSN 1367-5931.