FXIIa-IN-5 (Compound 4J) is an orally active, selective inhibitor for factor XIIa ( FXIIa ), with IC 50 of 21 nM. FXIIa-IN-5 inhibits the intrinsic coagulation pathways, and exhibits anti-inflammatory and antithrombotic activity in Carrageenan -induced mice thrombosis models. FXIIa-IN-5 exhibits moderate pharmacokinetic characteristics and slightly toxicity (at 100 mg/kg).