Heparin Dosage

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Usual Adult Dose for Deep Vein Thrombosis

Continuous IV Infusion: 5000 units IV one time as a bolus dose followed by 1300 units/hour by continuous IV infusion. Alternatively, a bolus dose of 80 units/kg IV one time followed by 18 units/kg/hour by continuous IV infusion may be used.
Intermittent subcutaneous injection: 17,500 units subcutaneously every 12 hours.
The dosage should be adjusted to maintain the aPTT at 1.5 to 2.5 times control.

Usual Adult Dose for Deep Vein Thrombosis - Prophylaxis

5000 units subcutaneously every 8 to 12 hours. This dosage may be adjusted to maintain the aPTT at the upper end of the normal range.

Usual Adult Dose for Pulmonary Embolism

Continuous IV Infusion: 5000 units IV one time as a bolus dose followed by 1300 units/hour by continuous IV infusion. Alternatively, a bolus dose of 80 units/kg IV one time followed by 18 units/kg/hour by continuous IV infusion may be used.
If it is suspected that the patient has experienced a massive pulmonary embolism, a more appropriate initial dosage may be an IV bolus of 10,000 units followed by 1500 units/hour.
Intermittent subcutaneous injection: 17,500 units subcutaneously every 12 hours.
The dosage should be adjusted to maintain the aPTT at 1.5 to 2.5 times control.

Usual Adult Dose for Myocardial Infarction

5000 units IV one time as a bolus dose followed by 1000 units/hour by continuous IV infusion.

Usual Adult Dose for Angina Pectoris

5000 units IV one time as a bolus dose followed by 1000 units/hour by continuous IV infusion.

Usual Adult Dose for Anticoagulation During Pregnancy

5000 units subcutaneously every 12 hours. This dosage may be adjusted to maintain the 6-hour aPTT at 1.5 times control or greater.

Usual Adult Dose for Thrombotic/Thromboembolic Disorder

100 units/mL every 6 to 8 hours for PVC catheters and peripheral heparin locks. Additional flushes should be given when stagnant blood is observed in catheter, after catheter is used for drug or blood administration, and after blood withdrawal from catheter.

Addition of 0.5 to 1 unit/mL to peripheral and central TPN has been shown to increase duration of line patency. Arterial lines are heparinized with a final concentration of 1 unit/mL.

Usual Pediatric Dose for Thrombotic/Thromboembolic Disorder

IV line flush:
Infant Dose: 10 units/mL every 6 to 8 hours.

Child Dose: 100 units/mL every 6 to 8 hours for PVC catheters and peripheral heparin locks. Additional flushes should be given when stagnant blood is observed in catheter, after catheter is used for drug or blood administration, and after blood withdrawal from catheter.

Addition of 0.5 to 1 unit/mL to peripheral and central TPN has been shown to increase duration of line patency. Arterial lines are heparinized with a final concentration of 1 unit/mL.

Renal Dose Adjustments

Data not available

Liver Dose Adjustments

Data not available

Dose Adjustments

For overweight patients, dosages are calculated based on ideal body weight. The following protocols may be useful in determining appropriate dosage adjustments.
aPTTx control less than 1.3:
Bolus 5,000 units Hold Infusion no Rate Change greater than 200 units/hr
aPTTx control 1.3 to 1.5:
Bolus no Hold Infusion no Rate Change greater than 100 units/hr
aPTTx control 1.5 to 2.5:
Bolus no Hold Infusion no Rate Change none
aPTTx control 2.5 to 3.5:
Bolus no Hold Infusion 30 to 60 min Rate Change less than 100 units/hr
aPTTx control greater than 3.5:
Bolus no Hold Infusion 1 to 2 hrs Rate Change less than 200 units/hr

aPTTx control less than 1.3:
Bolus 80 units/kg Hold Infusion no Rate Change greater than 4 units/kg/hr
aPTTx control 1.3 to 1.5:
Bolus 40 units/kg Hold Infusion no Rate Change greater than 2 units/kg/hr
aPTTx control 1.5 to 2.5:
Bolus no Hold Infusion no Rate Change none
aPTTx control 2.5 to 3.5:
Bolus no Hold Infusion no Rate Change less than 2 units/kg/hr
aPTTx control greater than 3.5:
Bolus no Hold Infusion 1 hr Rate Change less than 3 units/kg/hr

Precautions

Do not administer heparin, preserved with benzyl alcohol to neonates, infants, pregnant women, or nursing mothers. Benzyl alcohol has been associated with serious adverse events and death, particularly in pediatric patients. Heparin, preservative free, when indicated, should be used in these populations.

Heparin use is not recommended in the presence of severe thrombocytopenia or uncontrollable active bleeding, except in the case of disseminated intravascular coagulation. Heparin should be used with extreme caution in patients in whom there is an increased danger of hemorrhage, including those with severe hypertension, subacute bacterial endocarditis, hemophilia, some vascular purpuras, gastrointestinal ulcerations and continuous tube drainage of the stomach or small intestine, severe liver disease with impaired hemostasis, and menstruation. Heparin should be used with caution during or immediately following lumbar puncture or major surgery involving the brain, spinal cord, or eyes.

The dosage of heparin should be regulated by frequent blood coagulation tests when heparin sodium is administered in therapeutic amounts. Heparin sodium should be promptly discontinued if the coagulation test is unduly prolonged or if hemorrhage occurs.

Thrombocytopenia has been reported in patients receiving heparin with an incidence of 0 to 30%. During heparin administration, platelet counts should be obtained at baseline and periodically. Mild thrombocytopenia (count greater than 100,000/mm3) may remain stable or reverse even if heparin therapy is continued. However, thrombocytopenia of any degree should be closely monitored. If the platelet count falls below 100,000/mm3 or if recurrent thrombosis develops, the heparin product should be discontinued and, if required, an alternative anticoagulant administered.

Heparin-induced thrombocytopenia (HIT) is a serious antibody-mediated reaction resulting from irreversible platelet aggregation. HIT may progress to the development of venous and arterial thromboses, which is a condition referred to as heparin-induced thrombocytopenia and thrombosis (HITT). These events include deep vein thrombosis, cerebral vein thrombosis, limb ischemia, mesenteric thrombosis, renal arterial stenosis, skin necrosis, gangrene of extremities that may lead to amputation, myocardial infarction, pulmonary embolism, stroke, and possibly death. Thrombocytopenia of any degree should be closely monitored. If recurrent thrombosis develops or if the platelet count falls below 100,000/mm3, the heparin product should be promptly discontinued and alternative anticoagulants considered if patients require continued anticoagulation therapy.

Heparin-induced thrombocytopenia and heparin-induced thrombocytopenia and thrombosis can occur up to several weeks after heparin therapy is discontinued. Patients presenting with thrombosis or thrombocytopenia after heparin is discontinued should be evaluated for HIT and HITT.

Increased resistance to heparin is frequently encountered in patients experiencing fever, thrombosis, thrombophlebitis, infections from thrombosing tendencies, myocardial infarction, cancer, and in postsurgical patients.

Heparin should not be given by intramuscular injection. Intramuscular administration of other medications should be avoided in patients receiving heparin due to an increased risk of bleeding and hematoma at the injection site.

Cross-reactivity between porcine and bovine preparations as well as between unfractionated and low molecular weight heparins may occur.

An increased incidence of bleeding has been reported in patients greater than 60 years of age (especially women). Lower dosages of heparin may be indicated in such patients.

Periodic platelet counts, hematocrits, and tests for occult blood in stool are recommended during the entire course of heparin therapy.

Carefully examine all heparin injection vials to confirm choice of the correct strength prior to administration of the drug. Pediatric patients, including neonates, have died as a result of medication errors in which heparin injection vials have been confused with "catheter lock flush" vials.

Dialysis

Data not available

Other Comments

Heparin therapy is typically continued for 5 to 10 days. Oral anticoagulation with warfarin should be initiated 4 to 5 days prior to discontinuing heparin. The activated partial thromboplastin time (aPTT) should be drawn 6 hours after the initial bolus dose and following any changes in dose. Once the aPTT is stabilized, daily monitoring is recommended. The therapeutic range of heparin is considered to be an aPTT of 1.5 to 2.5 times normal, which corresponds to a plasma heparin concentration of 200 to 400 units/L determined by protamine titration.

Hemorrhage as well as thrombocytopenia may occur during heparin therapy and are associated with significant morbidity and mortality. Daily monitoring of platelet count, hematocrit, and complete blood count is recommended. A platelet count of less than 100,000/mm³ or a marked, progressive decline in platelet count is indicative of antibody-mediated platelet destruction and necessitates discontinuation of therapy.

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