Trypsin-like serine protease inhibitors, and their preparation and use

A method of treating or preventing blood loss, said method comprising administering to a subject in need thereof a compound of the formula (I)

• or a salt thereof,
• wherein
• R1 is optionally present one or more times and each R1 is, independently, hydrogen or COOR5;
• R2 is an optionally substituted ring system wherein said ring system is an aromatic or nonaromatic cyclic or bicyclic system comprising 5-13 carbon atoms;
• R3 is an optionally substituted ring system wherein said ring system is selected from (i) an aromatic cyclic system comprising 5-6 carbon atoms, and (ii) an aromatic heterocycle comprising 3-5 carbon atoms and 1-2 nitrogen atoms, a nitrogen oxide, oxygen atom, or sulfur atom;
• R4 is optionally present one or more times and each R4 is, independently, hydrogen or a halogen;
• R5 is hydrogen, a branched or linear lower alkyl group comprising 1-6 carbon atoms, a branched or linear aminoalkyl residue comprising 1-6 carbon atoms, a halogen or pseudohalogen residue, or a polyethylene glycol residue of the formula (II) or (III):
• CH3—O—(CH2—CH2—O—)n—CH2—CH2—(C═O)—NH—CH2— (II)
• CH3—O—(CH2—CH2—O—)n—CH2—CH2—NH—(C═O)—CH2—CH2—(C═O)—NH—CH2— (III)
• wherein said polyethylene glycol residue has a molecular weight of from 750 Da to 10,000 Da, and n is an integer from 25 to 250;
• o=1, 2 or 3;
• p=0, 1, 2, 3 or 4;
• i=0 or 1.