Synonyms in a broader sense
Phenprocoumon (active ingredient name), coumarins, vitamin K antagonists (inhibitors), anticoagulants, anticoagulants
How does Marcumar® work?
The drug known under the trade name Marcumar® contains the active ingredient phenprocoumon, which belongs to the main group of coumarins (vitamin K antagonists). The coumarins are molecules that have a suppressive effect on the natural processes of blood coagulation and thus inhibit the coagulation of the blood (blood coagulation inhibitors). Marcumar® is generally used to prevent thrombosis.
This may be necessary in the context of implanting artificial heart valves or vascular bypasses, after heart attacks or in the case of chronic cardiac arrhythmia. During natural blood coagulation, cascade-like activation processes of various blood coagulation factors take place in the organism. This means that certain blood clotting factors start to act one after the other and then activate each other.
Among other things, factors II, VII, IX and X are essential for the smooth course of hemostasis. The special feature of these blood clotting factors is the fact that they are all vitamin-K dependent (Memory aid: Vitamin-K dependent blood clotting factors 1972 = “nine, ten, seven, two”) and can therefore be inhibited by Marcumar®. These factors are carboxylated at a specific amino acid residue (glutamyl) by vitamin-K, which means that a carboxyl group is added.
By this Carboxyllierung the Vitamin K-dependent clotting factors are to be bound in addition in a the position particularly effectively to calcium ions and to advance the blood clotting thereby. However, since this carboxylation reaction changes the chemical structure of vitamin K, a mechanism is needed that can restore the vitamin’s original state. Coumarins in general and Marcumar® in particular now act as competitive inhibitors on an enzyme called vitamin K epoxide reductase, which performs exactly this task.
Competitive in this context means that the drug competes with the altered vitamin K for a binding site on the enzyme and thus enormously reduces the probability of restoring vitamin K. The effect of Marcumar® is therefore based on a reduction of the vitamin K level in the organism and the resulting prevention of carboxylation of the blood coagulation factors II, VII, IX and X. The factors thus remain inactive or can only be activated to a very limited extent. Consequently, the normal course of blood coagulation is drastically interfered with, no coagulation inhibition is the result.
Because of this mechanism of action, Marcumar® belongs to a group of blood-clotting inhibitors known as “vitamin K antagonists”. In contrast to other blood-clotting inhibiting medicines, the effect of coumarins (including Marcumar®) is only very delayed. This is justified in the fact that Vitamin K antagonists can unfold an effect only if the natural supply of Vitamin K and carboxylated, fully activatable coagulation factors is used up. For this reason, they cannot be used in acute emergency situations, but only in cases of long-lasting, chronic blood coagulation disorders or for the prevention of thromboses. Since the long-term intake of Marcumar® has a lasting effect on the vitamin K metabolism, care must be taken during use to ensure a sufficient, but not excessive, supply of the vitamin.
