Anticoagulants - Mechanism Of Action, List Of Drugs

2024 Author: Josephine Shorter | [email protected]. Last modified: 2024-01-07 17:49

Anticoagulants: a list of drugs

Anticoagulants are drugs that are aimed at suppressing the activity of the blood system, which is responsible for its clotting. Anticoagulants help keep the fibrin produced in small amounts, thereby preventing blood clots from forming. Anticoagulants inhibit blood clotting processes, changing its viscosity.

Drugs related to anticoagulants are prescribed for both therapeutic and prophylactic purposes. They are available in the form of tablets, ointments and solutions for intravenous and intramuscular administration. The doctor prescribes anticoagulants, choosing the dosage necessary for the patient. If the therapeutic scheme is not drawn up correctly, then you can seriously harm the body. The consequences are very serious, up to and including death.

Cardiovascular disease ranks first among the pathological causes of death among the human population. Often, blood clots lead to the death of a person suffering from cardiac pathology. Almost every second person has a blood clot in the vessels during the autopsy. In addition, pulmonary embolism and venous thrombosis can lead to serious health complications and disable people. Therefore, after one or another pathology of the cardiovascular system has been detected in a person, doctors prescribe anticoagulants to patients. If you start to undergo therapy in a timely manner, it will be possible to prevent the formation of thrombotic masses in the vessels, their blockage and other serious complications of the disease.

A natural anticoagulant known to many people is hirudin. This substance is found in the saliva of leeches. It works for 2 hours. Modern pharmacology offers patients synthetic anticoagulants, of which there are more than 100 names at the moment. Such a wide selection of drugs allows you to choose the most effective and efficient medication in each case.

Most often, anticoagulants have an effect not on the blood clot itself, but on the blood coagulation system, lowering its activity, which makes it possible to suppress the plasma factors of the blood, which cause it to clot, and also prevents thrombin from being produced. Without this enzyme, the fibrin filaments that make up the thrombus cannot grow. Thus, it is possible to slow down the process of thrombus formation.

Content:

• Indications for the use of anticoagulants
• How do anticoagulants work?

• Direct anticoagulants

  • Ointments and gels with heparin
  • Heparin for subcutaneous administration
  • Thrombin inhibitors
• Indirect anticoagulants
• Contraindications for use
• Side effects
• Antiplatelet agents

Indications for the use of anticoagulants

Anticoagulants are prescribed in the following cases:

• Stroke against the background of embolism or blockage of blood vessels by thrombotic masses.
• Myocardial infarction.
• Atherosclerotic vascular lesions.
• Rheumatic heart disease.
• Thrombophlebitis.
• Mitral valve disease.
• Thrombosis in the acute stage.
• Varicose veins.
• Aortic aneurysm.
• Ischemic heart disease.
• Pulmonary embolism.
• DIC syndrome.
• Thromboangiitis and obliterating endarteritis.
• Atrial fibrillation.

If a person takes anticoagulants without medical supervision, then this is associated with the risk of developing severe complications, up to hemorrhagic hemorrhages in the brain. If the patient has a predisposition to bleeding, then antiplatelet drugs should be used for his treatment, which are distinguished by a gentle effect on the body and do not cause such complications.

[Video] What drugs are used in anticoagulant therapy?

How do anticoagulants work?

Depending on the mechanism of action, anticoagulants are divided into direct and indirect:

• Direct anticoagulants reduce the activity of thrombin itself, deactivating prothrombin, thereby preventing the formation of blood clots. However, taking them is associated with the risk of developing internal bleeding, therefore, it is necessary to monitor the indicators of the blood coagulation system. Direct anticoagulants are well absorbed in the intestines, reach the liver through the blood, spread throughout the body, and then are excreted by the kidneys.

• Indirect anticoagulants affect the enzymes that are responsible for blood clotting. They completely eliminate thrombin, and do not suppress its activity. Also, these drugs improve the work of the myocardium, promote relaxation of smooth muscles, allow you to remove urates and excess cholesterol from the body. In connection with these therapeutic effects, indirect anticoagulants are prescribed not only for the treatment of thrombosis, but also for their prevention. These drugs are indicated for oral administration. With a sharp refusal from their use, an increase in the level of thrombin is observed, which provokes thrombosis.

There are also drugs that affect the blood clotting ability, but they work in a slightly different way. These drugs include acetylsalicylic acid, etc.

Direct anticoagulants

Heparin. This drug is the most common direct-acting anticoagulant. Medicines based on it are no less popular. Heparin prevents platelets from sticking to each other, increases blood flow to the kidneys and heart muscle. However, one should not exclude the possibility of blood clots formation while taking Heparin, since it interacts with plasma proteins and macrophages.

Taking the drug allows you to reduce blood pressure, has an anti-sclerotic effect, increases the permeability of the vascular wall, does not allow smooth muscle cells to carry out proliferative processes. Heparin also has a depressing effect on the immune system, promotes increased urine output and the development of osteoporosis. For the first time, this substance was obtained from the liver, which follows from its name.

If the drug is used to prevent thrombosis, then it is administered subcutaneously. In case of emergency, Heparin is administered intravenously. You can also use gels and ointments that contain Heparin. They have an antithrombotic effect, helping to reduce the inflammatory response. It is applied to the skin with a thin layer, gently rubbing.

Ointments and gels with heparin

Lyoton gel, Hepatrombin, Heparin ointment, Trombless, Lavenum, Venolife, Venitan Forte, Troxevasin are ointments that are used for the local treatment of thrombosis and thrombophlebitis.

However, during the use of drugs based on Heparin, it should be borne in mind that the risk of bleeding increases, since the process of thrombus formation is inhibited, and the permeability of the vascular wall increases.

Subcutaneous heparin (low molecular weight)

The drugs, which are called low molecular weight heparins, are distinguished by high bioavailability and sufficient activity against blood clots. They last longer than regular heparins, and the risk of bleeding is lower.

Low molecular weight heparins are rapidly absorbed and remain in the blood for a long time. They interfere with the production of thrombin, but at the same time do not make the vascular wall overly permeable. The use of drugs of this group makes it possible to improve blood flow, increase blood supply to internal organs, and normalize their performance.

The use of low-molecular-weight heparins is not associated with a high risk of complications, therefore, they displace conventional heparin from modern medical practice. The drugs are injected under the skin into the lateral surface of the abdominal wall.

Representatives of low molecular weight heparins are:

• Fragmin. The drug is produced in the form of a solution that has little effect on primary hemostasis and platelet adhesion processes. The drug is administered only intravenously, its intramuscular use is prohibited. It is prescribed to patients in the early postoperative period, provided that there is a risk of bleeding or severe platelet dysfunction is detected.
• Clevarin. This is a drug that is a direct anticoagulant. It prevents blood from clotting, thereby preventing the development of thromboembolism.
• Clexane. This drug prevents the formation of blood clots, and also helps to relieve the inflammatory response. It is not combined with other drugs that affect hemostasis.
• Fraxiparine. This drug prevents blood from clotting and promotes resorption of blood clots. After its introduction, bruises and nodules form at the injection site. After a few days, they dissolve on their own. If at the initial stage of the therapy the patient was given too much dose, then this can provoke the development of bleeding and thrombocytopenia, but in the future these side effects disappear on their own.
• Vesel Douai F. This preparation has a natural basis, as it is obtained from the intestinal mucosa of animals. It is used to reduce the level of fibrinogen in the blood, for resorption of thrombotic masses. For prophylactic purposes, it is used when there is a risk of blood clots in the veins and arteries.
• Analogues: Gemapaxan (sodium enoxaparin), Troparin (sodium heparin).

Drugs related to low molecular weight heparins require strict adherence to instructions. Their independent appointment and use is unacceptable.

Thrombin inhibitors

Thrombin inhibitors include the drug Hirudin. It contains a component that is present in the saliva of leeches. The drug begins to act in the blood, directly inhibiting thrombin production.

There are also preparations that contain a synthetic protein similar to that which was isolated from the saliva of leeches. These medicines are called Girugen and Girulog. These are new drugs that have several advantages over heparins. They last longer, so scientists are currently working on the creation of these drugs in tablet form. In practice, Girugen is rarely used, since the drug is expensive.

• Lepirudin is a drug used to prevent thrombosis and thromboembolism. It inhibits the production of thrombin and belongs to direct anticoagulants. Thanks to the intake of Lepirudin, it is possible to reduce the risks of developing myocardial infarction, as well as to refuse surgery for patients with exertional angina.
• Bivalirudin is a selective direct thrombin inhibitor and is a synthetic intravenous hirudin.

Indirect anticoagulants

Indirect anticoagulants include drugs such as:

• Phenilin. This drug is well absorbed and distributed in the body, quickly penetrates through all histohematogenous barriers and concentrates in the right place. Phenylin is considered one of the most effective drugs from the group of indirect anticoagulants. Its reception allows you to improve the rheological properties of blood, to normalize its ability to coagulate. The treatment with Phenilin allows you to eliminate convulsions, improve the general well-being of the patient. However, the drug is rarely prescribed, since its use is associated with the risk of developing many side effects.
• Neodikumarin - the drug prevents the formation of blood clots. The therapeutic effect develops as the drug accumulates in the body. Its reception allows you to reduce blood clotting, increase the permeability of the vascular wall. You need to take the drug strictly at a certain time, without violating the dosage regimen.
• Warfarin is the most commonly used anticoagulant, which interferes with the production of clotting factors in the liver, thereby preventing platelets from clotting. Warfarin has a fast healing effect. When the drug is finished, its side effects will also quickly be stopped.
• Syncumar is a vitamin K antagonist. Sold in pill form. The maximum effect is observed 24-48 hours after ingestion.

Contraindications for use

Contraindications for taking anticoagulants:

• Peptic ulcer disease.
• Hemorrhoids that are complicated by the discharge of blood.
• Hepatitis and fibrotic changes in the liver of a chronic course.
• Hepatic and renal failure.
• Urolithiasis.
• Thrombocytopenic purpura.
• Pericarditis and endocarditis.
• Acute lack of ascorbic acid and vitamin K in the body.
• Cavernous pulmonary tuberculosis.
• The presence of a malignant tumor in the body.
• Hemorrhagic pancreatitis.
• Aneurysm of the brain.
• Leukemia.
• Myocardial infarction with high blood pressure.
• Alcoholism.
• Crohn's disease.
• Hemorrhagic retinopathy.

Do not prescribe anticoagulants to pregnant women, nursing mothers, women during menstrual bleeding, and immediately after childbirth. It is not recommended to take drugs of this group for the elderly.

Side effects

Among the side effects from taking anticoagulants, the following can be distinguished:

• Dyspeptic disorders.
• Intoxication of the body.
• Allergic reactions
• Tissue necrosis.
• Skin rashes and itching.
• Disorders of the kidneys.
• Osteoporosis.
• Baldness.

The most formidable complication of anticoagulant treatment is hemorrhage in internal organs: mouth, nasopharynx, intestines, stomach, joints and muscles. There may be blood in the urine. To prevent these complications, it is necessary to monitor the blood picture of the patient receiving anticoagulants, as well as monitor his condition in general.

Antiplatelet agents

Antiplatelet agents are drugs that are designed to reduce blood clotting by preventing platelets from sticking together. They are prescribed in conjunction with anticoagulants in order to enhance the therapeutic effect in terms of preventing the formation of blood clots.

Antiplatelet agents allow you to expand the lumen of blood vessels, relieve pain and inflammation.

The most common anticoagulants include:

• Aspirin. The drug is available in tablet form, so it can be taken at home. The drug has a vasodilating effect, prevents platelets from sticking together, prevents the formation of blood clots.
• Ticlopidine. This drug prevents platelet adhesion, prolongs bleeding time, and improves blood circulation in small vessels. It is prescribed for ischemic heart disease, myocardial infarction, and cerebrovascular disease. The goal of the therapy is to prevent blood clots from forming.
• Tirofiban. This drug is often prescribed in a complex treatment regimen together with Heparin, which makes it possible to more effectively prevent the process of blood clots formation.
• Dipyridamole. This drug helps to expand the lumen of the coronary vessels, thins the blood, improves nutrition of the heart muscle and brain, and helps to lower blood pressure.

Read more: Antiplatelet agents - mechanism of action, list of drugs

The author of the article: Shutov Maxim Evgenievich | Hematologist

Education: In 2013 he graduated from the Kursk State Medical University and received a diploma "General Medicine". After 2 years, completed residency in the specialty "Oncology". In 2016 completed postgraduate studies at the National Medical and Surgical Center named after N. I. Pirogov.