Heparin injection

How does it work?

Heparin sodium injection is a type of medicine called an anticoagulant. It is used to stop blood clots forming within the blood vessels. Heparin sodium is sometimes referred to as standard or unfractionated heparin.

Blood clots normally only form to stop bleeding that has occurred as a result of injury to the tissues. The clotting process is complicated and begins when blood cells called platelets clump together and produce chemicals that activate the clotting process. The final part of this process involves a substance called thrombin being activated to produce a protein called fibrin. Fibrin binds the platelets together, forming a blood clot. This is the body’s natural way of repairing itself.

Heparin works by inactivating thrombin in the clotting process. This stops the formation of fibrin and so stops blood clots forming. Heparin is used to treat blood clots that have formed abnormally inside the blood vessels. It can also be used to prevent these types of dangerous blood clots.

A blood clot that forms abnormally within the blood vessels is known as a thrombus. It can be dangerous because the clot may detach and travel in the bloodstream (where it becomes known as an embolus) and may eventually get lodged in a blood vessel, thereby blocking the blood supply to a vital organ such as the heart, brain or lungs. This is known as a thromboembolism.

Some people have an increased tendency for blood clots to form within the blood vessels. This is usually due to a disturbance in the blood flow within the blood vessels. For example, in coronary artery disease, fatty deposits (atherosclerosis) on the walls of the coronary arteries can disrupt the blood flow, giving a tendency for platelets to clump together and start off the clotting process. Unstable coronary artery disease means that a furred up bit of the artery has ruptured and a clot has formed on it, reducing the flow of blood to the heart. This causes chest pain (angina) and can result in a heart attack.

Slow blood flow in the leg and pelvic veins can also result in clots forming in these blood vessels (deep vein thrombosis). These clots can break off and travel to the lungs (pulmonary embolism). Being immobile for long periods of time, for example due to a severe medical condition or following surgery, can increase the risk of these types of blood clot, as can pregnancy, obesity and certain blood disorders.

Heparin is given by injection or drip into a vein (intravenously) or by injection under the skin (subcutaneously) to treat and prevent these types of blood clots. The dose and length of treatment used will depend on the nature of the clot being treated or prevented.

What is it used for?

Treating and preventing blood clots in the veins of the leg (deep vein thrombosis).

Treating and preventing blood clots travelling to the lungs (pulmonary embolism).

Treating blood clots in the coronary arteries in unstable angina.

Treating blood clots that are blocking a peripheral artery, eg in the leg (peripheral arterial occlusion).

Preventing further blood clots in the heart immediately following a heart attack.

Preventing blood from clotting when it is filtered through an 'artificial kidney' (haemodialysis) machine as part of the management of kidney failure.

Preventing blood from clotting when it is filtered through a machine during heart-lung bypass surgery.

Warning!

While you are receiving treatment for a blood clot with this medicine you will need to have regular blood tests, usually on a daily basis, to check the length of time it takes your blood to clot. This is so that your dose can be adjusted to ensure that the lowest effective dose is used at all times, thus reducing the risk of bleeding.

If you receive this medicine for longer than five days you will need to have regular blood tests to check the level of blood cells called platelets in your blood. This is because heparin can sometimes cause the number of platelets in your blood to fall - a condition known as thrombocytopenia. If this happens, the heparin will need to be stopped and alternative treatment used.

The amount of potassium in your blood will also be checked in the blood tests, particularly if you have been receiving heparin for longer than seven days. This is because heparin can sometimes cause the amount of potassium in your blood to rise too high. This is called hyperkalaemia. Some people may be at a greater risk of this, for example those with diabetes or kidney problems, or people taking other medicines that can cause potassium to be retained in the body.

Use with caution in

Elderly people

Decreased liver function

Decreased kidney function

Chronic kidney failure

Diabetes mellitus

High level of potassium in the blood (hyperkalaemia)

Increase in the acidity of the blood (metabolic acidosis)

Hypersensitivity to low molecular weight heparins, eg dalteparin.

Not to be used in

People with low numbers of blood cells called platelets in their blood (thrombocytopenia)

People who have previously developed a reduced platelet count due to treatment with heparin (heparin-associated thrombocytopenia)

People who are actively bleeding

People who are more prone to bleeding than normal, eg due to the blood clotting disorder haemophilia

Peptic ulcer

Very high blood pressure

Bacterial infection of the heart valves and the lining surrounding the heart (bacterial endocarditis)

People who have recently had bleeding in the brain (cerebral haemorrhage), eg a haemorrhagic stroke

People who have had recent injury or surgery to the brain, spinal cord, or eyes

People who are due to have spinal or epidural anaesthesia or lumbar puncture

Severe liver disease.

This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy. If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

Pregnancy and Breastfeeding

Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

Heparin is often used to prevent blood clots in pregnant women who are at high risk of clots, for example due to a blood clotting disorder or because they have an artificial heart valve. Heparin does not cross the placenta and so does not enter the baby's bloodstream. It does not cause birth defects. However, some multidose vials of heparin contain benzyl alcohol and this should be avoided during pregnancy. Long-term use of heparin during pregnancy can cause weakening of the mother's bones (osteoporosis). There may also be an increased risk of bleeding during the pregnancy, or after delivery. You should discuss this with your doctor. As with all medicines, heparin should only be use during pregnancy if the benefits outweigh any possible risks.

Heparin does not pass into breast milk. It can be used safely in mothers who are breastfeeding.

Side effects

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.

Bleeding

High blood potassium level (hyperkalaemia)

Decrease in the number of platelets in the blood (thrombocytopenia)

Breakdown of skin cells

Thinning of the bones (osteoporosis) with long term use

Hair loss (alopecia) may be experienced after prolonged use

Blood clots in the spinal cord (spinal haematoma) in people having spinal or epidural anaesthesia or lumbar puncture while receiving heparin.

The side effects listed above may not include all of the side effects reported by the drug's manufacturer. For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.

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