Heparin calcium
Questions | Reviews
Dose for blood transfusion storage...
We're looking for confirmation that we can use heparin to store refrigerated whole blood for emergency transfusion in a developing world practice without many resources. We believe the dose is 2000u per 500 ml of whole blood. Is this correct? Regards,...
by James Li, M.D., 03/03/2006
Classification:
Anticoagulant
Action/Kinetics:
Anticoagulants do not dissolve previously formed clots, but they do forestall their enlargement and prevent new clots from forming. Heparin potentiates the inhibitory action of antithrombin III on various coagulation factors including factors IIa, IXa, Xa, XIa, and XIIa. This occurs due to the formation of a complex with and causing a conformational change in the antithrombin III molecule. Inhibition of factor Xa results in interference with thrombin generation; thus, the action of thrombin in coagulation is inhibited. Heparin also increases the rate of formation of antithrombin III-thrombin complex causing inactivation of thrombin and preventing the conversion of fibrinogen to fibrin. By inhibiting the activation of fibrin-stabilizing factor by thrombin, heparin also prevents formation of a stable fibrin clot. Therapeutic doses of heparin prolong thrombin time, whole blood clotting time, activated clotting time, and PTT. Heparin also decreases the levels of triglycerides by releasing lipoprotein lipase from tissues; the resultant hydrolysis of triglycerides causes increased blood levels of free fatty acids.
Onset: IV, immediate;
deep SC: 20-60 min.
Peak plasma levels, after SC: 2-4 hr.
t
1/2: 30-180 min in healthy persons. t
1/2 increases with dose, severe renal disease, and cirrhosis and in anephric clients and decreases with pulmonary embolism and liver impairment other than cirrhosis.
Metabolism: Probably by reticuloendothelial system although up to 50% is excreted unchanged in the urine. Clotting time returns to normal within 2-6 hr.
Uses:
Pulmonary embolism, peripheral arterial embolism, prophylaxis, and treatment of venous thrombosis and its extension. Atrial fibrillation with embolization. Diagnosis and treatment of disseminated intravascular coagulation. Low doses to prevent deep venous thrombosis and pulmonary embolism in pregnant clients with a history of thromboembolism, urology clients over 40 years of age, clients with stroke or heart failure, AMI or pulmonary infection, high-risk surgery clients, moderate and high-risk gynecologic clients with no malignancy, neurology clients with extracranial problems, and clients with severe musculoskeletal trauma. Prophylaxis of clotting in blood transfusions, extracorporeal circulation, dialysis procedures, blood samples for lab tests, and arterial and heart surgery.
Investigational: Prophylaxis of post-MI, CVAs, and LV thrombi. By continuous infusion to treat myocardial ischemia in unstable angina refractory to usual treatment. Adjunct to treat coronary occlusion with AMI. Prophylaxis of cerebral thrombosis in evolving stroke.
Contraindications:
Active bleeding, blood dyscrasias (or other disorders characterized by bleeding tendencies such as hemophilia), clients with frail or weakened blood vessels, purpura, thrombocytopenia, liver disease with hypoprothrombinemia, suspected intracranial hemorrhage, suppurative thrombophlebitis, inaccessible ulcerative lesions (especially of the GI tract), open wounds, extensive denudation of the skin, and increased capillary permeability (as in ascorbic acid deficiency). IM use.
Special Concerns:
Use with caution in menstruation, in pregnant women (because they may cause hypoprothrombinemia in the infant), during lactation, during the postpartum period, and following cerebrovascular accidents. Geriatric clients may be more susceptible to developing bleeding complications, unusual hair loss, and itching.
Side Effects:
CV:
Hemorrhage ranging from minor local ecchymoses to major hemorrhagic complications from any organ or tissue. Higher incidence is seen in women over 60 years of age. Hemorrhagic reactions are more likely to occur in prophylactic administration during surgery than in the treatment of thromboembolic disease. White clot syndrome.
Hematologic: Thrombocytopenia (both early and late).
Hypersensitivity: Chills, fever, urticaria are the most common. Rarely, asthma, lacrimation, headache, N&V;, rhinitis,
shock, anaphylaxis. Allergic vasospastic reaction within 6-10 days after initiation of therapy (lasts 4-6 hr) including painful, ischemic, cyanotic limbs. Use a test dose of 1,000 units in clients with a history of asthma or allergic disease.
Miscellaneous: Hyperkalemia, cutaneous necrosis, osteoporosis (after long-term high doses), delayed transient alopecia, priapism, suppressed aldosterone synthesis. Discontinuance of heparin has resulted in rebound hyperlipemia.
Following
IM (usual), SC: Local irritation, erythema, mild pain, ulceration, hematoma, and tissue sloughing.
Laboratory Test Alterations:
AST and ALT.
Overdose Management:
Symptoms: Nosebleeds, hematuria, tarry stools, petechiae, and easy bruising may be the first signs.
Treatment: Drug withdrawal is usually sufficient to correct heparin overdosage. Protamine sulfate (1%) solution; each mg of protamine neutralizes about 100 USP heparin units.
Drug Interactions:
How Supplied:
Dosage
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