SSR182289 (SSR182289A free base) is a selective and potent orally active thrombin inhibitor. SSR182289 competitively and selectivity inhibits human thrombin ( K i =0.031 μM). SSR182289 demonstrates anticoagulant activity in vitro ( thrombin time EC 100 =96 nM) and inhibits tissue factor-induced thrombin generation (IC 50 =0.15 μM) in human plasma. SSR182289 inhibits thrombin-induced aggregation of human platelets (IC 50 =32 nM), but has no effect on aggregation induced by other platelet agonists.