What are the guidelines for Heparin (unfractionated heparin) infusion?

From the Guidelines

Heparin infusion should be initiated with a weight-based protocol starting with a bolus of 80 units/kg followed by a continuous infusion at 18 units/kg/hour, as recommended by the most recent guidelines 1. This approach is supported by the latest evidence, which suggests that weight-based dosing is effective in treating venous thromboembolic disease (VTE) and has a favorable safety profile.

Key Considerations

• The initial dosing of unfractionated heparin (UFH) in the treatment of VTE is weight-based, with a recommended regimen of 80 units/kg bolus followed by 18 units/kg per hour infusion, as stated in the guidelines 1.
• Activated Partial Thromboplastin Time (aPTT) should be monitored 6 hours after starting therapy and the infusion rate adjusted to maintain an aPTT of 1.5-2.5 times the control value (typically 60-80 seconds) 1.
• For dose adjustments, a standardized protocol should be followed: for subtherapeutic aPTT, give a bolus of 80 units/kg and increase the rate by 2-4 units/kg/hour; for supratherapeutic aPTT, hold the infusion for 1 hour if aPTT is significantly elevated (>100 seconds) and decrease the rate by 2-3 units/kg/hour 1.
• Patients require daily monitoring of platelet counts to detect heparin-induced thrombocytopenia, and proper IV access and use of an infusion pump are essential for accurate delivery 1.

Special Considerations

• Lower doses may be needed for patients with renal impairment, liver disease, or those at high bleeding risk, as heparin is primarily metabolized by the liver and its clearance is affected by renal function 1.
• UFH is contraindicated in patients with heparin-induced thrombocytopenia (HIT) and should only be used with extreme caution in patients with a history of HIT, as alternative anticoagulants such as direct thrombin inhibitors (DTIs) or fondaparinux may be preferred 1.

From the FDA Drug Label

2.3 Therapeutic Anticoagulant Effect with Full-Dose Heparin The dosing recommendations in Table 1 are based on clinical experience be adjusted for the individual patient according to the results of suitable laboratory tests, the following dosage schedules may be used as guidelines: Table 1: Recommended Adult Full-Dose Heparin Regimens for Therapeutic Anticoagulant Effect *Based on 68 kg patient

METHOD OF ADMINISTRATION	FREQUENCY	RECOMMENDED DOSE
Deep Subcutaneous (Intrafat) Injection	Every 8 hours or	8,000 to 10,000 units of a concentrated solution
Every 12 hours	15,000 to 20,000 units of a concentrated solution
Intermittent Intravenous Injection	Every 4 to 6 hours	5,000 to 10,000 units, either undiluted or in 50 to 100 mL of 0.9% Sodium Chloride Injection, USP
Continuous Intravenous Infusion	Continuous	20,000 to 40,000 units/24 hours in 1,000 mL of 0.9% Sodium Chloride Injection, USP

The guidelines for heparin infusion are as follows:

• Initial dose: 5,000 units by intravenous injection
• Continuous infusion: 20,000 to 40,000 units/24 hours in 1,000 mL of 0.9% Sodium Chloride Injection, USP
• Monitoring: Adjust the dosage of Heparin Sodium Injection according to the patient's coagulation test results, with aPTT target of 1.5 to 2 times normal. 2

From the Research

Heparin Infusion Guidelines

• The American College of Chest Physicians recommends that unfractionated heparin (UFH) be administered based on actual body weight, with a therapeutic range for activated partial thromboplastin time (aPTT) that is site-specific and validated 3.
• For patients with non-ST-segment elevation acute coronary syndromes, the initial UFH dosing should be based on weight-adjusted bolus and infusion dosing, with a recommended bolus dose of 60-70 U/kg and an infusion dose of 12-15 U/kg/h 4, 5.
• Excess weight-adjusted UFH dosing has been associated with an increased risk of major bleeding, particularly in elderly and female patients 4.
• In morbidly obese patients, UFH infusion rates should be adjusted based on actual body weight, with a mean infusion rate of 11.5 units/kg/h required to obtain a first therapeutic aPTT 6.
• The use of anti-factor Xa monitoring may be superior to aPTT measurement in patients with apparent heparin resistance or those with severe obesity or renal insufficiency 3.
• Protamine may be used to reverse bleeding related to low-molecular-weight heparin (LMWH), although it may not fully normalize anti-factor Xa activity 3, 7.
• A heparin-binding copolymer has been developed as a potential antidote to reverse the effects of UFH, LMWH, and fondaparinux, with a promising efficacy and safety profile 7.

Key Considerations

• UFH dosing should be individualized based on patient weight and renal function.
• Regular monitoring of aPTT and anti-factor Xa activity is necessary to ensure therapeutic efficacy and minimize the risk of bleeding.
• The use of LMWH may be preferred over UFH in certain patient populations, such as those with severe obesity or renal insufficiency, due to its more predictable pharmacokinetic and pharmacodynamic properties 3.

Patient-Specific Factors

• Age and sex may influence the risk of bleeding associated with UFH dosing, with elderly and female patients at higher risk 4.
• Renal function should be considered when selecting an anticoagulant, with UFH preferred over LMWH in patients with severe renal impairment 3.
• Obesity may require adjusted UFH infusion rates, with morbidly obese patients requiring smaller infusion rates per kilogram actual body weight 6.