Heparin is a commonly-used blood thinning medication to prevent blood clotting. It is used to prevent possible blood clots and the risk of embolism in the heart, legs and lungs. Heparin is also used before or after the operation, during blood transfusion/kidney dialysis, and to prevent the blood sample collected in a tube from clotting. It is usually given via injection; its most significant side effect is excessive bleeding. Other side effects include thrombocytopenia (decreased platelet count in the circulation) and hypersensitivity reactions. It may cause osteoporosis in long-term use.
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Heparin is a prescription anticoagulant medication used to prevent blood clot formation, and for the treatment of cardiac, pulmonary and circulatory disorders that carry the risk of clot formation. Naturally synthesized form in the liver and lung tissues is a mix of mucopolysaccharides (sugar molecule derivative).
Commercial heparin is mostly obtained from cow lungs or swine intestines. As it is poorly absorbed from the intestines, it should only be injected via intravenous or subcutaneous route, and should not be injected via intramuscular route.
This test in which a blood sample taken from a vein in your arm is used measures the anti-Xa activity, thereby, assessing the levels of low molecular weight heparin (LMWH) and standard heparin (SH). Heparin molecules change in size and activity; SH consists of different sizes of heparin molecules, and LMWH consists of small heparin molecules.
Coagulation tests performed during treatment help choose the proper dose of heparin. Conditions which may increase the risk of bleeding are checked before using heparin:
Anti-Xa results should be interpreted based on the type and timing of the heparin used, and the underlying condition to be treated. Different laboratories may give different results for the same sample. Usually, if the concentrations of SH and LMWH are within the specified dose range, excessive bleeding is not observed.
If the patient does not use heparin, anti-Xa levels should be 0 or at undetectable levels. A high anti-Xa level means that the patient is receiving overdose, and the risk of bleeding presents; and a low level indicates the necessity of increasing the heparin dose.
Plasma heparin levels and aPTT (assessment of the clotting time) might be higher in older individuals despite comparable heparin doses. Elevated aPTT means late coagulation, and decreased aPTT means faster-than-normal clotting; normal range is 30 to 40 seconds.
Heparin is used for the treatment of following diseases:
Heparin is not effective when taken orally; it should be given via intermittent intravenous injection (into the vein), intravenous infusion or deep subcutaneous (under the skin) injection. Sometimes, it is administered 1 to 6 times a day; sometimes it is given as a slow, continuous injection into the vein. Intravenous form should only be used in the hospitals.
After the administration of the first subcutaneous injection in the hospital, training should be given on how to inject the medication to allow the patients administer the remaining doses at home. There are different administration protocols for the adjustment of the heparin dose. One of these is based on infusion dose, and the therapeutic aPTT level is 60 to 85 seconds; another one is based on body weight.
Anticoagulant medications include standard (unfractionated) heparin (SH), low molecular weight heparin (LMWH), vitamin K antagonists (VKAs) and novel oral anticoagulants (NOAC). Commonly used anticoagulant treatment consists of a short intravenous (IV) heparin treatment for 5-7 days followed by oral anticoagulant treatment for 3-6 months.
In this approach, limiting the period of IV heparin treatment to 7 days reduces the risk of heparin-induced thrombocytopenia (HIT). This risk increases with the increasing treatment period; thereby, potassium levels should be assessed if the heparin treatment lasts more than a week. If the patient received heparin within the last 100 days, platelet count should be assessed before and 24 hours after the treatment.
Heparin is injected to upper arm or abdominal region via subcutaneous injection; and can be injected into the veins. There is no oral form of heparin, however, there are some blood thinning medications in tablet form.
Based on the form and the administration frequency of the medications; the dosage and administration should be individualized in line with age, severity of the underlying condition, and other comorbidities. The dose is usually initiated based on the ideal body weight, and the following doses are adjusted based on the body’s response. Studies in children are lacking, however, the dose is adjusted based on the body weight and medical history. The risk of bleeding is high in patients over the age 60, the starting dose should be low.
While the dose should be adjusted based on the results of the laboratory tests for each patient, the following dosage schedules can be used as guides:
Operation is a risk factor for clot formation. Heparin is used to reduce the risk of clotting before and after the operation, and usually discontinued when the patient is discharged. The most commonly used dosage is 5000 unit via subcutaneous route 2 hours before the operation followed by 5000 unit every 8-12 hours for 7 days or until the patient is completely mobile. It is administered via deep subcutaneous injection into the arm or abdomen using a fine needle to minimize the tissue trauma.
Heparin may interact with certain foods, herbs and vitamins. If you are using heparin you should be careful when consuming the following foods and vitamins:
Bacteria in the yogurt increase the production of vitamin K, people using heparin should not consume yogurt at large amounts.
It may interact with aspirin, anti-inflammatory medications (NSAIDs) and other medications affecting the blood coagulation. Consult with your doctor before using any other medication.
You must inform your doctor if you have one or more of the following disorders:
Inform your doctor at once if you are experiencing symptoms including death of the skin tissue at the injection site, shaking, fever, urticaria, itching, burning, shortness of breath, chest pain, and swelling of the face, lips, throat and tongue. Heparin may also cause reactions in individuals sensitive to meat products and swine protein.
As heparin does not cross placenta, it is preferred in pregnant women when anticoagulant treatment is necessary, however, some studies have demonstrated adverse effects in the infants of mothers who used heparin. Preservative-containing forms of heparin which normally does not cross placenta may cause nervous system deceleration, breathing difficulty and changes in blood chemistry in some infants.
The risk of bleeding is especially higher in women above 60 years old. As it contains benzyl alcohol, it is not recommended to be used in newborns.
Do not use if the solution is cloudy or containing particles.
Heparin is for short-term treatment, if you do not use it as recommended, it may pose serious risks. If you miss a dose; use it as soon as you remember, never use two doses together at the same time. In case of overdose, dangerous levels of medication which may cause severe bleeding may accumulate in your body.
Be careful when using sharp objects such as razor and nail clipper, and when using toothbrush, dental floss or toothpick.
Smoking reduces your plasma heparin level, alcohol increases the risk of bleeding. As heparin contains sodium, inform your doctor about conditions which may get worse with salt use such as congestive heart failure.
These side effects are not always observed, and even if observed, they mostly resolve within a few days or weeks. However, if they become severe, you should seek medical help.
References: 1- Heparin Injection, 2- Information on Heparin, 3- Heparin Importation