April
23
23:00
Hematology

Anticoagulants of indirect action: indications and contraindications.

Anticoagulants - are drugs that prevent the formation of blood clots in the vessels.This group includes two subgroups of drugs: anticoagulants of direct and indirect action.About anticoagulants of direct action we have already talked before.In the same article, we briefly describe the principle of the normal functioning of the blood coagulation system.To better understand the mechanisms of action of indirect anticoagulants, we strongly recommend the reader to become familiar with the information available, that takes place in the normal - knowing it will be easier to focus in on what phase of the clotting action is described below drugs and what are theprovided their effects.

Content

  • 1 mechanism of action of indirect anticoagulants
  • 2 pharmacokinetics and pharmacodynamics of indirect anticoagulants
  • 3 Indications and contraindications for use
  • 4 Features and application of indirect anticoagulants
    • 4.1 neodikumarina (pelentan, Trombarin, Dikumaril)
    • 4.2 acenocoumarol (sinkumar)
    • 4.3 phenindione (Fenilin) ​​
    • 4.4 Warfarin (warfarin)

Drugs in thisgroups are effective only when directly introduced into the body.Upon mixing them with blood in vitro clotting they have no influence.The action is not directly on the blood clot, and influence the coagulation system through the liver, causing a series of biochemical reactions that result in developing the state, similar to vitamin deficiencies K. As a consequence, reduces the activity of the plasma clotting factor, thrombin is formed more slowly and, therefore, slower formsthrombus.

Anticoagulants of indirect action: indications and contraindications. well and quickly these drugs are absorbed in the gastrointestinal tract.With the bloodstream reach various organs, mainly the liver, where they exert their effects.
speed start, duration of effect and half-life in different drugs of this class vary.

excreted primarily in the urine.Some representatives of the class of urine stains pink.

anticoagulant effect of drugs in this group have by interfering with the synthesis of clotting factors than gradually reduce the speed of this process.In addition to the anticoagulant effect of these drugs reduce muscle tone bronchus and intestine, increase the permeability of the vessel walls, reduce blood lipids, inhibit the reaction of antigen with antibody, stimulate the excretion of uric acid.

Anticoagulants of indirect action: indications and contraindications. Anticoagulants of indirect action are used for the prevention and treatment of thrombosis and thromboembolism in the following conditions:

Contraindications to the use of drugs of this group are:

Unlike anticoagulants of direct action, the effect of the drugs in this group is not immediately, andas the accumulation of the active substance in organs and tissues, ie slowly.They act, on the contrary, is longer.Speed, strength and extent of accumulation (accumulation) of various drugs of this class varies.

are used exclusively inside, or orally.Intramuscularly, subcutaneously or intravenously can not use them.

discontinue therapy with anticoagulants of indirect action should not once, but gradually - slowly reducing the dose and increasing the time between doses of the drug (up to 1 times per day, or even every other day).Abrupt withdrawal of the drug may result in a sudden compensatory increase in blood levels of prothrombin and cause thrombosis.

Anticoagulants of indirect action: indications and contraindications. If overdose of this group or their application too long, they can cause bleeding, and it is associated not only with a reduction of blood clotting, but also with an increase in the permeability of the capillary walls.Less common in this situation developed bleeding from the mouth and throat, gastrointestinal bleeding, bleeding in the muscles and joints of the cavity, as well as blood appears in the urine - micro- or gross hematuria.

To avoid complications of the above, it is necessary during treatment with anticoagulants of indirect action to closely monitor the condition of the patient and laboratory parameters of blood clotting.Once in 2-3 days, and in some cases, often is necessary to determine the prothrombin time and examine urine for the presence of red blood cells (hematuria, i.e. the presence of blood in urine, - one of the first signs of drug overdose).For a more complete control in addition to the content of prothrombin in the blood should be determined and other indicators: tolerance to heparin, recalcification time, prothrombin index, plasma fibrinogen, prothrombin content of 2-step method.

should not be administered concurrently with these drug formulations salicylates group (especially acetyl salicylic acid) since they enhance the concentration of free anti-coagulant in the blood.

drugs of indirect anticoagulants actually a bit.It neodikumarin, acenocoumarol, warfarin and phenindione.
consider each of them in detail.

When ingestion absorbed relatively quickly, half-life of 2.5 hours, excreted in the urine is not in its original form, as well as metabolic products.

expected effect of the drug begins to appear 2-3 hours after administration, reaching a peak during the period of 12-30 hours and continues for another two days after discontinuation of the drug.

used alone or in addition to heparin.

release form - pill.

Doziruyut according to the scheme, the maximum daily dose - 0.9 g dose is adjusted depending on the performance of the prothrombin time.

Anticoagulants of indirect action: indications and contraindications. well absorbed when taken orally.It has a cumulative effect (that is valid when the tissue gather sufficient amount).Maximum effect is observed 24-48 hours after initiation of treatment with this drug.After the cancellation of his normal level of prothrombin is determined by 48-96 hours.

release form - pill.

Is inside.On the first day recommended dose is 8-16 mg, after the dosage depends on the values ​​of prothrombin.Generally, the maintenance dose - 1-6 mg per day.
possible increased sensitivity of the patient to the drug.In case of allergic reactions, it must be canceled.

Anticoagulants of indirect action: indications and contraindications. diminishing of blood clotting observed after 8-10 hours after ingestion, reaches a maximum of about a day.It possesses strong cumulative effect.

release form - pill.

initial dose is in the first 2 days at 0.03-0.05 g three times a day.Further dosages of the drug are selected individually depending on the blood parameters: prothrombin index should not be equal to less than 40-50%.The maximum single dose - 0.05 grams daily - 200 mg.

The treatment fenilinom possible skin staining and discoloration of urine.In case of these symptoms should be replaced phenindione other anticoagulants.

Anticoagulants of indirect action: indications and contraindications. in the gastrointestinal tract completely absorbed.The half-life is 40 hours.The anticoagulant effect starts 3-5 days after the start of treatment and continues during 3-5 days after discontinuation of the drug.

Available in tablets.
Started treatment with 10 mg 1 time per day, 2 days the dosage was reduced in 1.5-2 times - up to 5-7.5 mg.The therapy is carried out under the supervision of the index of blood INR (international normalized ratio).In some clinical situations, such as in preparation for surgery, the recommended dosage of the drug vary and are determined individually.

Strengthen the anticoagulant effect of warfarin aspirin and other nonsteroidal anti-inflammatory agents: heparin, dipyridamole, simvastatin.Effect weaken cholestyramine, vitamin K, laxatives, a large dose of paracetamol.

Anticoagulants of indirect action - this is a very serious preparations which, if they unprofessional reception can cause a number of serious, even life-threatening, complications.Located above information is provided only for the purpose of review.In no case do not set yourself or your family, these drugs alone: ​​to determine whether they are necessary to you, and choose efficient and safe dosage can be a doctor!

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