The invention provides methods of making and using compounds of the formula: or a pharmaceutically acceptable salt thereof; wherein n is an integer between 1 and 2 inclusively; m is an integer between 0 and 2 inclusively; X is selected from the group consisting of CH or N; R1 is selected from the group consisting of —CH2NH2, and R2 is selected from the group consisting of —H, —OH, —NH2 and acetyl; R3 is selected from the group consisting of —H, benzyloxycarbonyl and benzylsulfonyl; and R4 is selected from the group consisting of —OH, wherein p is an integer between 0 and 2 inclusively, Y is selected from the group consisting of —O—, —S—, —S(═O)—, —SO2—, methylene, —CH(OH)—, —CH(NH2)—, —CH(CH2—OH)—, —CH(CH2—NH2)— or —N(R6)—, R5 is selected from the group consisting of —H or a simple (C1-C3) alkyl and R6 is selected from the group consisting of —H, a simple (C1-C3) alkyl or a simple (C1-C3) acyl. These compounds are useful as anticoagulant agents as a result of their selective dual inhibition of thrombin and prothrombinase.