Phenprocoumon (drug name), coumarins, vitamin K antagonists (inhibitors), anticoagulants, anticoagulants
The medicinal product known under the trade name Marcumar® contains the active substance phenprocoumone, which is considered to be the main group of coumarins (vitamin K antagonists).
The coumarins are molecules that have an oppressive effect on the natural processes of blood coagulation and thus inhibit the coagulation of the blood (anticoagulants).
Marcumar ® is commonly used to prevent thrombosis, which may be necessary in the context of implantation of artificial heart valves or vascular bypasses, after heart attacks or in chronic cardiac arrhythmias.
During natural blood clotting, cascade-like activation processes of various blood coagulation factors take place in the organism. This means that certain blood coagulation factors will act in sequence and then activate each other.
Among other factors, Factors II, VII, IX and X are essential for the smooth flow of hemostasis. The special feature of these blood coagulation factors is the fact that they are all vitamin K dependent (hint: Vitamin K dependent blood clotting factors 1972 = "nine, ten, seven, two") and can therefore be inhibited by Marcumar ® .
These factors are carboxylated at a particular amino acid residue (glutamyl) by vitamin K, which means that a carboxyl group is added. By means of this carboxylation, the vitamin K-dependent coagulation factors are able to bind particularly effectively to calcium ions and thereby promote blood coagulation.
Since in this carboxylation reaction, however, the vitamin K is changed in its chemical structure, it requires a mechanism that can restore the initial state of the vitamin.
Cumarine in general and Marcumar ® in particular now act as competitive inhibitors to an enzyme called vitamin K-epoxide reductase, which does exactly this job.
Competitive in this context means that the drug competes with the altered vitamin K for a binding site on the enzyme and thus greatly reduces the recovery probability of vitamin K.
The effect of Marcumar® is therefore based on a lowering of the vitamin K level in the organism and a resulting prevention of the 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. In the normal course of blood clotting is therefore drastically intervened, no clotting inhibition is the result.
Marcumar ® is one of the anticoagulants belonging to a group called "vitamin K antagonists" due to this mechanism of action.
In contrast to other anticoagulant drugs, the effect of coumarins (including Marcumar ® ) is delayed.
This is due to the fact that vitamin K antagonists can only have an effect when the natural supply of vitamin K and carboxylated, fully activatable clotting factors is used up.
For this reason, they can not be used in acute emergency situations, but only in long-lasting, chronic blood coagulation disorders or for the prevention of thrombosis.
Since the long-term use of Marcumar ® has a lasting effect on the vitamin K metabolism, a sufficient but not excessive intake of the vitamin should be taken into account during the application.
Undesirable effects are not excluded, often accompanying symptoms such as nausea, vomiting, stomach pain, loss of appetite and diarrhea. In some patients, after prolonged treatment with Marcumar ®, constipation, increased hair loss, bruising, and even unwanted bleeding tendencies have occurred.
The most serious side effects include bleeding within the skull (intracerebral hemorrhage, cerebral hemorrhage) and high blood pressure.
After the Marcumar ® has been discontinued, it may take 10 to 14 days for the anti-coagulant effect to disappear and the normal coagulation process to resume. This fact can be explained by the fact that only after this time can a sufficiently high concentration of carboxylated coagulation factors be formed.
In emergency situations, it is therefore necessary to supply the missing coagulation factors II, VII, IX and X to the organism externally in order to limit a possible risk of bleeding.
Also in connection with planned surgical interventions and dental treatments, it must always be remembered to discontinue the anticoagulant medicine early enough and thus to prevent an increased tendency to bleed.
Marcumar® works by inhibiting the formation of certain so-called coagulation factors in the liver. It blocks the vitamin K necessary for their production. As a result, the blood is "diluted" or, more precisely, its tendency to coagulate is slowed down.
The desired effect is that in the vessels do not form dangerous blood clots (thrombi), which can otherwise lead to a vascular occlusion. According to the mechanism of action of Marcumar®bzw. Its active ingredient Phenprocoumon can be used to neutralize the effect of the drug by supplying vitamin K to the patient. This can either be swallowed or administered via the vein directly into the blood. Due to the excess of VItamin K in the liver, the anticoagulant effect of Marcumar® is thereby eliminated. In this way, for example, a tendency to bleed caused by an overdose is treated.
Marcumar also works with diarrhea, but the mode of action can sometimes be heavily influenced. With pronounced diarrheal disease, the intake of vitamin K from the diet may be reduced. In proportion, it may now come to an excess of the active ingredient of Marcumar® in the liver, which inhibits the function of vitamin K. As a result, it can lead to an excessive inhibition of blood clotting and therefore a tendency to bleed. Therefore, the treating physician should be informed when diarrhea occurs in a patient taking Marcumar®. If necessary, then more frequent checks of the coagulation values and a corresponding adjustment of the dosage should take place.