What is the typical starting dose for subcutaneous unfractionated heparin (UFH) for prophylaxis?

Subcutaneous UFH Dosing for VTE Prophylaxis

The standard starting dose for subcutaneous unfractionated heparin (UFH) for VTE prophylaxis is 5000 units administered every 8 hours (three times daily). 1, 2

Dosing Recommendations Based on Clinical Setting

General Medical/Surgical Patients

• Standard prophylactic dose: 5000 units subcutaneously every 8 hours 1
• This three-times-daily regimen is more effective than twice-daily dosing in preventing DVT in general surgery patients 1, 2
• While 5000 units every 12 hours has also been used, it appears less effective, particularly in oncologic surgery 1

Pregnancy and Postpartum

• Dosing varies by trimester during pregnancy 1:
  • First trimester: 5000 units subcutaneously every 12 hours
  • Second trimester: 7500 units subcutaneously every 12 hours
  • Third trimester: 10,000 units subcutaneously every 12 hours
• Postpartum: 5000 units subcutaneously every 8-12 hours 1

Special Populations

Patients with Renal Impairment

• UFH is the preferred agent for VTE prophylaxis in patients with severe renal dysfunction (creatinine clearance < 30 mL/min) 1, 2
• Standard dosing of 5000 units subcutaneously every 8 hours can be used without adjustment 2
• UFH is preferred over LMWH in this population because the liver is the main site of heparin biotransformation 1, 2

Obese Patients

• Limited data suggests higher doses may be needed for obese patients 3
• However, a study comparing 7500 units vs 5000 units every 8 hours in obese patients did not demonstrate a statistically significant reduction in VTE rates 3

Administration Considerations

Timing with Neuraxial Anesthesia

• First prophylactic UFH dose should be administered no sooner than 1 hour after needle/catheter placement 1
• In patients receiving preoperative prophylactic UFH, neuraxial puncture/catheter manipulation or removal should not occur within 4-6 hours after UFH administration 1
• Subsequent UFH administration may occur no earlier than 1 hour after catheter removal 1

Duration of Prophylaxis

• For medical patients: Continue for the length of hospital stay or until fully ambulatory 1
• For surgical patients: Continue for at least 7-10 days 1
• Extended prophylaxis for up to 4 weeks should be considered for high-risk patients 1, 2

Contraindications and Alternatives

• UFH is contraindicated in patients with heparin-induced thrombocytopenia (HIT) 1, 2
• For patients with a history of HIT, consider alternatives such as direct thrombin inhibitors or fondaparinux 2
• For patients at high risk of bleeding, consider mechanical prophylaxis with intermittent pneumatic compression devices 2

Monitoring

• Routine coagulation monitoring is generally not necessary for prophylactic doses of UFH 4
• There is usually no need for daily monitoring of the effect of low-dose heparin in patients with normal coagulation parameters 4

The three-times-daily regimen (5000 units every 8 hours) is preferred over twice-daily dosing because it has been shown to be more effective in preventing DVT, particularly in high-risk surgical patients, despite a potentially higher risk of bleeding complications 1.