heparin

Actions and spectrum: 

heparin is a naturally occurring anticoagulant that works by increasing the activity of antithrombin III, a natural inhibitor of blood clotting. heparin has a broad spectrum of action and is used to prevent and treat blood clots in various conditions, such as deep vein thrombosis, pulmonary embolism, and myocardial infarction.

It is also used during surgeries, such as heart bypass surgery and dialysis, to prevent blood clots from forming. Additionally, heparin is used as a prophylaxis in high-risk patients, such as those with atrial fibrillation, and as a treatment for disseminated intravascular coagulation (DIC) and antiphospholipid syndrome. 

DRUG INTERACTION

Contraindicated  

Serious Use Alternative  

Monitor Closely  

Minor  

Frequency defined 

>10% 

possibly delayed, Heparin-induced thrombocytopenia (10-30%)  

Frequency not defined 

Hemorrhage 

Increased liver aminotransferase 

Immune hypersensitivity reaction 

Mild pain 

Injection site ulcer 

Anaphylaxis 

Osteoporosis  

Post marketing Reports 

Gasping syndrome 

Necrosis of skin 

serious adverse reactions 

Vascular disorders, including vasospastic reactions, contusion 

Delayed transient alopecia 

Rebound hyperlipemia 

heparin resistance 

Hypersensitivity 

Local irritation, mild pain, ulceration or hematoma, erythema 

Histamine-like reactions 

Hyperkalemia 

Priapism 

Black Box Warning: 

heparin has a black box warning for the risk of bleeding, which can be fatal. The use of heparin should be avoided in patients with uncontrolled bleeding or a history of heparin-induced thrombocytopenia (HIT). 

Contraindication/Caution: 

Contraindication: 

• Known hypersensitivity to heparin or pork products (heparin is derived from porcine intestinal mucosa) 
• Active major bleeding or conditions with a high risk of hemorrhage 
• Severe thrombocytopenia (platelet count < 100,000/mm3) 
• Uncontrolled arterial hypertension 
• Intracranial hemorrhage (except when caused by anticoagulants) 
• Bacterial endocarditis or other systemic infections 
• Severe liver or kidney disease 
• Recent eye, brain, or spinal cord surgery or lumbar puncture 
• Any condition that requires a lumbar puncture or spinal anesthesia, or any other procedures with the risk of bleeding in the central nervous system.

Caution: 

• Active bleeding or a history of bleeding disorders 
• Severe hypertension 
• Severe liver or kidney disease 
• Recent surgery or trauma 
• Bacterial endocarditis 
• Diabetes mellitus 
• Eye or brain surgery 
• Ulcerative colitis 
• Elderly patients 
• Women who are pregnant or breastfeeding

Comorbidities: 

heparin should be used under caution in patients with a history of bleeding disorders or in those with conditions that have an increased risk of bleeding, such as thrombocytopenia, severe hypertension, bacterial endocarditis, and gastrointestinal ulcers.

Patients with liver or kidney disease may require dose adjustments as heparin is eliminated through these organs. heparin should also be used with caution in patients with heparin-induced thrombocytopenia (HIT), as they may develop a life-threatening immune reaction upon re-exposure to heparin. 

Pregnancy consideration: US FDA pregnancy category: Not assigned 

Lactation: heparin is not known whether it is excreted into human milk  

Pregnancy category: 

• Category A: Satisfactory and well-controlled studies show no risk to the fetus in the first or later trimester. 
• Category B: There is no evidence of risk to the fetus found in animal reproduction studies and there are not enough studies on pregnant women. 
• Category C: Adverse effects on the fetus found with evidence in animal reproduction studies and no adequate evidence for an effect in humans, care must be taken for potential risks in pregnant women. 
• Category D: There is adequate data available with sufficient evidence of human fetal risk from various platforms, but despite potential risks may be used only in emergency cases for potential benefits. 
• Category X: Drugs listed in this category outweigh risks over benefits These category drugs should be prohibited for pregnant women. 
• Category N: There is no data available for the drug under this category. 

Pharmacology: 

heparin is a highly sulfated glycosaminoglycan that acts as an anticoagulant by binding to and activating antithrombin III (ATIII), a serine protease inhibitor that inactivates thrombin and factor Xa. By binding to ATIII, heparin enhances its ability to inactivate these clotting factors, leading to decreased thrombin generation and blood clot formation. 

heparin also has a secondary effect on fibrinolysis, the process by which blood clots are broken down. heparin binds to and activates heparin cofactor II (HCII), which in turn inactivates thrombin and some coagulation factors. This activates the fibrinolytic system by promoting the release of tissue plasminogen activator (tPA), leading to the breakdown of blood clots.  

Pharmacodynamics: 

heparin is an anticoagulant that works by increasing the activity of antithrombin III, a natural inhibitor of clotting factors such as thrombin and factor Xa. When heparin binds to antithrombin III, it causes a conformational change that enhances the inhibitory activity of antithrombin III against thrombin and factor Xa. This leads to the prevention of the conversion from fibrinogen to fibrin and the formation of blood clots. 

heparin has a rapid onset of action and works within minutes of administration. Its anticoagulant effect can be monitored using the activated partial thromboplastin time (aPTT) or anti-factor Xa activity tests. The duration of its anticoagulant effect varies depending on the dose and route of administration.  

Pharmacokinetics: 

Absorption 

When given subcutaneously, heparin is slowly and incompletely absorbed into the systemic circulation. The onset of action is delayed and varies depending on the dose and site of injection. Intravenous administration provides immediate therapeutic levels of heparin. 

Distribution 

heparin has a low volume of distribution due to its high affinity for plasma proteins, particularly antithrombin III. It does not cross the blood-brain barrier. 

Metabolism 

heparin is not metabolized in the liver or other organs. 

Elimination and excretion 

heparin is cleared from the circulation by the reticuloendothelial system and, to a lesser extent, by the kidneys. The elimination half-life of heparin is dose-dependent and ranges from 30 minutes to 2 hours. 

Administration: 

heparin can be administered via intravenous (IV) injection, subcutaneous (SC) injection, or continuous IV infusion. The route of administration depends on the indication for use and the desired onset and duration of action.

heparin injections are typically given in a hospital or clinical setting under the supervision of a healthcare provider. The dosage and administration of heparin may vary based on individual patient factors, such as weight, age, and medical condition. 

Patient information leaflet 

Generic Name: heparin 

Pronounced: [ HEP-a-rin ]  

Why do we use heparin? 

heparin is a medication used to prevent and treat blood clots. It is commonly used to prevent pulmonary embolism (PE) and deep vein thrombosis (DVT) in patients who are at risk, such as those who have undergone surgery or are confined to bed rest.

heparin is also used to treat certain types of heart attacks and unstable angina and to prevent blood clots from forming during certain medical procedures, such as dialysis and blood transfusions. In addition, heparin may be used to prevent blood clots in patients with atrial fibrillation or artificial heart valves.