The invention relates to the use of acylated 4-amidino- or 4-guanidinobenzylamine in accordance with the general formula IP4-P3-P2-P1 (I),where P4 is a monosubstituted or polysubstituted or unsubstituted benzylsulfonyl group, P3 is a monosubstituted or polysubstituted or unsubstituted, natural or unnatural α-amino acid or α-imino acid in the D configuration, P2 is a monosubstituted or polysubstituted or unsubstituted, natural or unnatural α-amino acid or α-imino acid in the L configuration, and P1 is a monosubstituted or polysubstituted or unsubstituted 4-amidino- or 4-guanidinobenzylamine group, for inhibiting plasma kallikrein (PK), factor XIa and factor XIIa, in particular for preventing the activation of coagulation at synthetic surfaces and for systemic administration as anticoagulants/antithrombotic agents, in particular for preventing the activation of coagulation at synthetic surfaces for the purpose of averting thromboembolic events.
