Anticoagulants

Anticoagulants, also known as anticoagulant drugs or anticoagulants, are drugs that inhibit hemostasis (blood clotting).
In a broader sense, drugs that have an inhibitory effect on platelet function (e.g. inhibitors of cyclooxygenase 1 such as acetylsalicylic acid or receptor antagonists of the platelet-derived adenosine phosphate receptor such as clopedigrel) are also known as anticoagulants. However, as platelet aggregation inhibitors they form a separate class of active substances and must be distinguished from anticoagulants in the narrower sense.

A distinction is made between them.

• direct anticoagulants (directly inhibit plasmatic coagulation)
• and
• indirect anticoagulants (inhibit plasmatic coagulation indirectly via a co-factor, or by inhibiting the synthesis of coagulation factors)
• A further classification can be made according to the type of application (oral or non-oral).

Anticoagulants are used therapeutically to prevent the intravascular formation of thrombi (thrombosis prophylaxis). They are mainly used perioperatively to reduce the risk of pulmonary embolism. Furthermore, the antiplatelet aggregation inhibitors are widely used for the prophylaxis of arterial thromboses.

The effect of the drugs also results in the essential side effect of all anticoagulants. Especially in case of overdose there is a risk of bleeding (e.g. hat bleeding, bleeding of the stomach, kidneys or brain bleeding).

To be distinguished.

• direct anticoagulants (directly inhibit plasmatic coagulation)
• and
• indirect anticoagulants (inhibit plasmatic coagulation indirectly via a co-factor, or by inhibiting the synthesis of coagulation factors)

A further classification can be made according to the type of application (oral or non-oral).

Heparins (parenterally administered glycosaminoglycans)

• Unfractionated heparin
• Low molecular weight (= fractionated) heparins
  • Certoparin
  • Dalteparin
  • Enoxaparin
  • Nadroparin
  • Reviparin
  • Tinzaparin.

Non-oral inhibitors of factor Xa (Stuart power factor) for s.c. injection

• Fondaparinux (Anixtra®)

Oral anticoagulants(NOAC = new oral anticoagulants or DOAC = direct oral anticoagulants). Direct oral anticoagulants intervene directly in the coagulation cascade and directly inhibit individual coagulation factors.

• Oral factor Xa inhibitors (Stuart power factor)
  • Apixaban (Eliquis®)
  • Rivaroxaban (Xarelto®)
  • Edoxaban (Lixiana®)
• Oral inhibitors of factor IIa(thrombin)
  • Dabigatran (Pradaxa®)
  • Argatroban®

Vitamin K antagonists (VKA)

• Coumarins (orally administered vitamin K antagonists)
  • Phenporcoumon = PPC (Marcumar®)

Other active substances (anticoagulants in the broad sense)

• Platelet aggregation inhibitor
  • Oral inhibitors of cyclooxygenase 1
    • Acetylsalicylic acid (ASS®)
• Oral antagonists of the thrombocytic adenosine phosphate receptor (thienopyridines)
  • Clopedrigel (Plavix®, Isocover®)
  • Prasugrel (Efient®)
• Inhibitors of the platelet glycoprotein II/GPIIIa receptor (i.v.)
  • Antibody fragment
    • Abciximab (ReoPro®)
  • Low molecular weight GPII/GPIIIa receptor antagonists
    • Etifibatide (Integrilin®)

The anticoagulants colloquially known as blood thinners are, misleadingly, also called "blood thinners". However, anticoagulants do not reduce the viscosity of the blood or the erythrocyte count of the hematocrit. Among the "blood thinners" is the group of plasma expanders.

1. Crowther MA et al: Mechanisms responsible for the failure of protamine to inactivate low-molecular-weight heparin. Br J Haematol 116:178-186.
2. Neumann HA (2014) The coagulation system. ABW Scientific Publisher GmbH Berlin.