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What Is Heparin Sodium?

B. Chisholm
B. Chisholm

Heparin sodium is an anticoagulant drug used to treat and prevent the formation of clots in the blood vessels. It is sometimes referred to as fractionated heparin and is given by injection. Heparin sodium is available in most countries by prescription only and is known by various trade names in different countries, according to manufacturer.

The blood clotting process in the body is a complicated cascade involving numerous blood cells and chemicals. Different anticoagulant drugs act at different stages of the coagulation process. Heparin sodium acts toward the end of the cascade. It inactivates thrombin, which is one of the chemicals involved in the formation of fibrin, which makes clots. By inhibiting thrombin, heparin sodium prevents the formation of fibrin and, therefore, clotting.


Blood clots can occur in patients due to numerous factors, including coronary artery disease, some blood disorders, or prolonged periods of restricted movement or bed rest, such as after an operation. They are potentially fatal, as they can travel through the blood stream and block organs such as the lung, heart or brain. Heparin sodium may prevent this.

It is administered intravenously into the veins or subcutaneously, under the skin. The dose and how often it is given is determined by what it is being used for and by each patient's response. This is usually measured by a blood test, the partial thromboplastin time (PTT). This basically measures how quickly the blood is clotting and determines whether the dosage needs to be adjusted.

As with any medication, heparin sodium may interact with other drugs and may not be used in patients with some clinical conditions. Any concomitant medicines, including homeopathic, over-the-counter and complementary drugs should be discussed with the prescribing doctor. Pregnancy, desired pregnancy and lactation should also be discussed. Heparin is contraindicated in patients with some bleeding disorders.

Adverse side effects may occur, including bleeding. It is for this reason that the blood will be closely monitored throughout treatment, and dosage adjusted accordingly. Heparin sodium is usually only administered to patients in hospital. Should any untoward reaction occur, medical attention should be sought immediately.

If prolonged anticoagulation therapy is needed, patients may be changed from heparin sodium to a low molecular weight heparin such as enoxaparin, which is a daily subcutaneous injection, or oral therapy, such as warfarin. The duration of anticoagulant treatment depends on the condition being treated. Some people may require lifelong anticoagulants, and monitoring of coagulation.

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