Summary
The elucidation of the structure of the antithrombin binding sequence in heparin has
given a large impulse to the rational design of heparin related drugs. De novo chemical synthesis of the corresponding pentasaccharide as well as simplified analogues
has provided very specific, antithrombin-mediated inhibitors of factor Xa with various
pharmacokinetic profiles. Fondaparinux and idraparinux are examples of such compounds
that have found clinical application as antithrombotics. Because of the very specific
binding to antithrombin the pharmacokinetics of pentasaccharides can be predicted
and transferred to other molecules covalently bound to them. The new chemical entities
thus obtained display a wide array of antithrombotic activities, giving improved heparin
molecules as well as new anticoagulants, devoid of the undesired side effects of heparin
and with unprecedented pharmacological profiles. In this context, a direct thrombin
inhibitor was covalently coupled to a pentasaccharide by an inert spacer.This compound,
EP42675 exerts antithrombin mediated anti-factor Xa activity together with direct
thrombin inhibiting capacity. It displays favourable pharmacokinetics as imposed by
the pentasaccharide. EP42675 was further modified by the introduction of a biotin
moiety in its structure.The new entity obtained, EP217609 exerts the same pharmacological
profile as EP42675 and it can be instantaneously neutralised by injection of avidin.
Due to this unprecedented mechanism of anticoagulant activity and its ability to be
neutralised,EP217609 deserves to be investigated in clinical settings where direct
thrombin inhibition is required.
Keywords
Antithrombin - coagulation inhibitors - drug design - heparin - thrombosis