Anti-thrombotic agents are used for treatment of thrombosis – to prevent a thrombus enlarging, or to prevent thrombosis in people at risk, such as those who have:

  • Atrial fibrillation

  • Blood disorders

  • Endocarditis

  • Mechanical heart valves

  • Mitral stenosis

  • Hip or knee replacements.

All anti-thrombotic agents produce a bleeding tendency and may cause post-operative bleeding. Dental preventive care is thus especially important in order to minimise the need for surgical intervention. In general, anti-thrombotic agents should be stopped before surgery only where the risk of post-operative bleeding is high (eg major surgery) or where the consequences of even minor bleeding are significant (eg retinal and intracranial surgery) though, for other minor surgery, drug dose reductions are rarely needed and indeed may put the patient at risk from thromboses which can be lethal.1 This should be discussed with the patient, who also must be warned of the risk of intra- and post-operative bleeding and intra/extra-oral bruising.

The two main classes of anti-thrombotic drugs are anticoagulants and antiplatelet drugs. Oral anticoagulants include:

  • Vitamin K antagonists (VKAs -such as warfarin/coumarins)

  • Newer oral anticoagulants (NOACs - such as dabigatran). The latter, such as direct thrombin inhibitors (DTI) (gatrans) and anti-Xa (xabans), target respectively the single coagulation enzymes thrombin (dabigatran) or factor Xa (apixaban, rivaroxaban, and edoxaban). In contrast to warfarin, NOACs have less thrombotic events and lower rates of major bleeding events and do not require monitoring in the same way as for warfarin using the prothrombin time or INR.2 and are thus replacing VKAs for many situations. Dabigatran and rivaroxaban are quickly absorbed and have short half-lives compared to warfarin so, in the event of excessive anticoagulant activity, discontinuing the drug is usually sufficient. Dabigatran and rivaroxaban have to date had no antidotes and if reversal is essential, haemodialysis, coagulation factor concentrates, and an antibody fragment which binds dabigatran (aDabi-Fab) were recommended to reverse the effects.3

The U.S. Food and Drug Administration (FDA) has now just granted approval of Praxbind (idarucizumab),4 a humanised antibody fragment, or Fab, which binds specifically to dabigatran molecules only, neutralising their anticoagulant effect without interfering with the blood coagulation cascade, for reversal of the dabigatran anticoagulant effects if needed for emergency surgery/urgent procedures or in life-threatening or uncontrolled bleeding.5,6

Biological agents clearly will have increasing utility in healthcare well beyond those already reported.