Brands, Medical Use, Clinical Data
Drug Category
- Fibrinolytic Agents
- Anticoagulants
- Heparins
Dosage Forms
- Solution for subcutaneous injection
- Intravenous injection
- Intravenous infusion
Brands / Synonyms
Alpha-Heparin; Ariven; Arteven; Bemiparin; Calcilean; Calciparine; Certoparin; Clexane; Clivarin; Clivarine; Dalteparin; Depo-Heparin; Enoxaparin; Enoxaparin sodium; Eparina [DCIT]; Fluxum; Fragmin A; Fragmin B; Fraxiparin; Hed-Heparin; Hepalean; Heparin; Heparin Cy 216; Heparin Leo; Heparin Lock Flush; Heparin sodium; Heparin sodium preservative Free; Heparin sodium salt; Heparin sulfate; Heparinate; Heparinic acid; Hepathrom; Leparan; Lipo-Hepin; Liquaemin; Liquaemin Sodium; Liquemin; Low molecular weight heparin sodium; Multiparin; Novoheparin; Pabyrin; Parnaparin; Parvoparin; Pularin; Reviparin; Sandoparin; Sodium heparin; Sublingula; Thromboliquine; Vetren; Vitrum AB
Indications
For anticoagulant therapy in prophylaxis and treatment of venous thrombosis and its extension, for prevention of post-operative deep venous thrombosis and pulmonary embolism and for the prevention of clotting in arterial and cardiac surgery.
Pharmacology
Heparin is a highly acidic mucopolysaccharide formed of equal parts of sulfated D-glucosamine and D-glucuronic acid with sulfaminic bridges. The molecular weight ranges from six to twenty thousand. Heparin occurs in and is obtained from liver, lung, mast cells, etc., of vertebrates. Heparin is a well known and commonly used anticoagulant which has antithrombotic properties. Heparin is indicated for the prophylaxis of deep vein thrombosis, which may lead to pulmonary embolism, and also for the prophylaxis of ischemic complications of unstable angina and non-Q-wave myocardial infarction, when concurrently administered with aspirin. Heparin inhibits reactions that lead to the clotting of blood and the formation of fibrin clots both in vitro and in vivo. Heparin acts at multiple sites in the normal coagulation system. Small amounts of Heparin in combination with antithrombin III (Heparin cofactor) can inhibit thrombosis by inactivating activated Factor X and inhibiting the conversion of prothrombin to thrombin. Once active thrombosis has developed, larger amounts of heparin can inhibit further coagulation by inactivating thrombin and preventing the conversion of fibrinogen to fibrin. Heparin also prevents the formation of a stable fibrin clot by inhibiting the activation of the fibrin stabilizing factor.
Mechanism of Action
The mechanism of action of heparin is antithrombin-dependent. It acts mainly by accelerating the rate of the neutralization of certain activated coagulation factors by antithrombin, but other mechanisms may also be involved. The antithrombotic effect of heparin is well correlated to the inhibition of factor Xa. Heparin interacts with antithrombin III, prothrombin and factor X.
Absorption
Some oral absorption but lack of anticoagulant effect. Rapidly taken up by endothelial cells with remainder bound to plasma proteins.
Toxicity
Heparin sodium - Mouse, median lethal dose greater than 5000 mg/kg. Another side effect is heparin induced thrombocytopenia (HIT syndrome). HIT is caused by an immunological reaction that makes platelets form clots within the blood vessels, thereby using up coagulation factors
Biotrnasformation / Drug Metabolism
Liver and the reticulo-endothelial system are the sites of biotransformation.
Contraindications
Heparin sodium should not be used in patients:
- With severe thrombocytopenia.
- In whom suitable blood coagulation tests e.g. the whole-blood clotting time, partial thromboplastin time, etc.
cannot be performed at appropriate intervals (this contraindication refers to full-dose heparin; there is usually
no need to monitor coagulation parameters in patients receiving low-dose heparin sodium).
- With an uncontrollable active bleeding state, except when this is due to disseminated intravascular
coagulation.
Drug Interactions
Drug Interactions:
a. Drugs Enhancing Heparin Effect:
Oral anticoagulants: Heparin sodium may prolong the one-stage prothrombin time. Therefore, when heparin sodium is
given with dicumarol or warfarin sodium, a period of at least 5 hours after the last intravenous dose or 24 hours
after the last subcutaneous dose should elapse before blood is drawn if a valid prothrombin time is to be
obtained.
Platelet inhibitors: Drugs such as acetylsalicylic acid, dextran, phenylbutazone, ibuprofen, indomethacin,
dipyridamole, hydroxychloroquine and others that interfere with platelet-aggregation reactions (the main hemostatic
defense of heparinized patients) may induce bleeding and should be used with caution in patients receiving heparin
sodium.
The anticoagulant effect of heparin is enhanced by concurrent treatment with antithrombin III (human) in
patients with hereditary antithrombin III deficiency. Thus in order to avoid bleeding, reduced dosage of heparin is
recommended during treatment with antithrombin III (human).
b. Drugs Decreasing Heparin Effect:
Digitalis, tetracyclines, nicotine, or antihistamines may partially counteract the anticoagulant action of heparin
sodium. Heparin Sodium Injection should not be mixed with doxorubicin, droperidol, ciprofloxacin, or mitoxantrone,
since it has been reported that these drugs are incompatible with heparin and a precipitate may form.
Drug/ Laboratory Tests Interactions
Hyperaminotransferasemia: Significant elevations of aminotransferase (SGOT [S-AST] and SGPT [S-ALT])
levels have occurred in a high percentage of patients (and healthy subjects) who have received heparin sodium. Since
aminotransferase determinations are important in the differential diagnosis of myocardial infarction, liver disease
and pulmonary emboli, rises that might be caused by drugs (heparin sodium) should be interpreted with caution.
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