Anticoagulant

The Administration of a drug to reduce blood clotting is called anticoagulation (Greek anti, " against" and Latin coagulatio " aggregation "). The drug is used anticoagulant ( anticoagulant, plural: anticoagulants, obsolete: anticoagulants ) called. The effect is due to an influence of the plasmatic coagulation, that is, the coagulation factors in the plasma. There are direct anticoagulants that inhibit directly with a clotting factors, distinguished from indirect anticoagulants, which either require a co-factor for anticoagulation or inhibit the synthesis of clotting factors. Typical representatives of direct anticoagulants, hirudin, and also designated as a new oral anticoagulant drugs such as apixaban, dabigatran and rivaroxaban. Classical representatives of indirect anticoagulants are the vitamin K antagonists and heparins.

Delineate Of the anticoagulants, platelet aggregation inhibitors such as aspirin and clopidogrel, which act by inhibiting the function of platelets and thus can clump the property of platelets, which interfere. The slang term "blood thinners" is misleading for both anticoagulants and antiplatelet agents for because these agents do not make the blood thinner in terms of a lower viscosity. An actual blood dilution represents the hemodilution, a method for the targeted reduction in hematocrit.

  • 3.1 Indirect anticoagulants 3.1.1 coumarins (vitamin K antagonists )
  • 3.1.2 heparins
  • 3.2.1 factor Xa inhibitor
  • 3.2.2 thrombin inhibitor

Reasons for anticoagulation

An anticoagulation is necessary for diseases or conditions in which a tendency to form blood clots (thrombi ) is present, and to avoid thrombosis or embolism in the arteries or in veins or treat.

Preventive (prophylactic indication)

Before, during and after surgery and at bed rest from other causes anticoagulants are often used to prevent thrombosis and pulmonary embolism. Even with cardiac catheterization procedures and blood sampling for Stammzellapherese and ( outside the human body ) in tube systems (dialysis, heart -lung machine ), or blood transport tube inhibition of blood coagulation is often required.

For treatment ( therapeutic indications )

The most common reason for therapeutic anticoagulation is the non- valvular atrial fibrillation or flutter. In this arrhythmia is an increased risk of embolism, which must be reduced in many patients through the inhibition of coagulation. Second most common reason thrombosis ( usually the leg veins), here is the anticoagulation in the acute phase to prevent the further extension of thrombosis and later a recurrence (relapse ). During the treatment in most patients after a thrombosis is only required for a few months, may be useful in some cases (eg in case of repeated thrombosis or congenital bleeding disorders such as APC resistance ) a lifelong anticoagulation. Here special consultations on the subject of coagulation can give to large hospitals and centers the patient important recommendations. Patients after heart valve surgery still require anticoagulation with biological valve prostheses often live long only for a few weeks or months, with artificial valves but usually.

Less common reasons for anticoagulation may be (eg after palliative surgery for congenital heart disease ), an advanced atherosclerosis (eg coronary heart disease, peripheral arterial disease, or narrowing of the carotid artery ), heart aneurysm or an atypical hemodynamics.

Anticoagulation and risk of bleeding

The main risk of a drug anticoagulation is the risk of bleeding. In particular, feared the hemorrhage, which faces a risk of oral anticoagulation the advantage of reducing the risk of ischemic stroke. For risk assessment to consider here is the risk of cerebral hemorrhage from other causes, the incidence of cerebral hemorrhage is located in Germany between 10 and 12/100.000 inhabitants.

To estimate the risk, there is a risk score, HAS- BLED score of.

From a score = 3, there is a relevant risk of bleeding that requires special care when prescribing anticoagulants.

Medicines and essential properties

From the effect of the medication results in the main side effect of all anticoagulants. Consists mainly of overdose the risk of bleeding (eg, gastrointestinal, renal, or cerebral hemorrhage ). The drugs can be divided according to the principle of action in direct and indirect anticoagulants in. Another classification can be done according to the type of application to be administered orally and not orally administered anticoagulants.

Indirect anticoagulants

Indirect anticoagulants inhibit plasmatic coagulation directly.

Coumarins (vitamin K antagonists )

The so-called " oral anticoagulation " with coumarins - such as phenprocoumon - takes the form of regular tablets, the dose, based on regular blood samples to determine the INR (formerly Quick) is set. The higher the INR, the more intense anticoagulation. In chronically ill reliable monitoring can be transmitted in the form of coagulation self-management on the patient. The necessary test equipment to be paid under certain conditions by health insurance. This allows the patient a reliable, but simple self-monitoring the correct dosage.

Oral anticoagulation is cheap and also an outpatient basis without any significant problems. The effect lasts for several days, which may be disadvantageous in bleeding or operations.

Heparins

The only parenterally administered heparins are glycosaminoglycans, their anticoagulant effect is due to an increase in activity of endogenous antithrombin. Antithrombin leads to inactivation of the procoagulant factor Xa. After the molecular weight between unfractionated heparin ( UFH) and low molecular weight heparin can be distinguished (LMWH ). While unfractionated heparin additionally accelerates the inactivation of the procoagulant thrombin also lose weight heparins with a molecular weight of 5400 u this ability.

The molecular weight affect the pharmacokinetics of the individual substances. In general, the molecular weight decreases the bioavailability and half-life increase. In addition, the chemical laboratory verifiability of the effect due to the aforementioned mechanisms of action differs. While the effect can be tested by unfractionated heparin by determining the partial thromboplastin time, low molecular weight heparins can be checked only through the anti-factor Xa activity.

Unfractionated heparin is administered subcutaneously twice daily or 2-3, then usually administered as a continuous infusion intravenously. The half-life is 30 to 60 minutes. The effect of unfractionated heparin diminishes rapidly and can be reversed by protamine quickly.

Low molecular weight ( = fractional ) heparins are derived from unfractionated heparin. Representatives of this group are Certoparin, dalteparin, enoxaparin, nadroparin, and tinzaparin Reviparin. Depending on the indication and preparation heparins are administered 1-2 times daily subcutaneously. The effect can be reversed by protamine to 50 to 85% depending on the employed short term LMWH preparation

Direct oral anticoagulants ( DOAK )

Direct oral anticoagulants are also known as new oral anticoagulants ( NOAK ). Herein, "new" to the decades- long single, more largely the same oral anticoagulants of the coumarin.

Factor Xa inhibitors

  • Apixaban
  • Rivaroxaban
  • Edoxaban

Thrombin inhibitors

  • Dabigatran
  • Ximelagatran was taken in February 2006 due to liver damage worldwide from the market.

Other active ingredients

  • Hirudin, a thrombin inhibitor (used with leeches )
  • Lepirudin, a recombinant hirudin
  • Bivalirudin, hirudin derived from Bluegeln
  • Calcium-chelating agent, such as citrate or EDTA, which by binding of calcium ( chelate ) to prevent clotting of the blood. Especially Citratantikoagulation finds increased use in continuous renal replacement therapy. The advantage is that the patient himself is exempt from the anti-coagulation, anticoagulation takes place only in the extracorporeal circuit. Thus, patients can be treated, which can not tolerate heparin (HIT II, TBI) or septic.
  • Fondaparinux
  • Argatroban
  • Otamixaban, factor Xa inhibitor, for intravenous administration

In the laboratory ( in vitro)

In the investigation of this blood is treated with anticoagulants such as EDTA, citrate, Ammoniumheparinat, lithium heparinate or Acid Citrate Dextrose (ACD ) to investigate unclotted blood can. Blood tubes used in blood collection are already equipped with one of these anticoagulants.

Hemodilution

The Antikogulanzien colloquially referred to as blood thinners are actually blood-thinning drugs to distinguish the plasma expander because Antikogulanzien neither the viscosity of the blood, nor the concentration of blood cells and whole blood protein decrease appreciably.

  • Plasma expanders can not swallow tablets as you, they are infused.
  • Plasma expander also reduce the clotting ability of the blood, this is an often unwelcome side effect. This side effect varies greatly depending depending on the substance class of if he solely by the concentration reduction of coagulation factors and platelets comes about (gelatin preparations),
  • Or pharmacologically related is ( starch preparations ).
  • Increasing volume in circulation in massive blood loss.
  • Reduction of viscosity at fresh strokes.

Procedure for atrial disease

A catheter implantation of an ear-tip ( Watchman Device) in the atrial appendage was successfully used as an alternative to anticoagulation.

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