Heparin

Trade names

Heparin

Actions

• Direct factor Xa inhibitor
• Direct thrombin inhibitor

Route of Administration

Intravenous or subcutaneous

Bioavailability

30% (if subcutaneous)

Plasma protein binding

~90%

Time to peak plasma concentration

4 h (if subcutaneous)

Half-life

1 h

Duration of action

Dose dependent (if subcutaneous)

Metabolism

Liver and the reticulo-endothelial system. Incompletely understood.

Elimination

Reticulo-endothelial system. A small fraction is excreted unchanged in urine.

Heparin cannot be eliminated by hemodialysis.

Recommended dose (IV)

Loading dose: 5000 IU

Maintenance dose: 500 IU/kg/day adjusted so that aPTT monitored every 4-6 hours is 2 to 3 times the control value.

Renal impairment

In patients with moderate to severe renal impairment reduce IV bolus to 2500 IU and follow with 200-400 IU/kg/day.

Hepatic impairment

In patients with moderate to severe hepatic impairment (Child-Pugh class B and C) reduce IV bolus to 2500 IU and follow with 200-400 IU/kg/day.

Discontinuation before invasive procedures

Stop heparin infusion at least 1 hour before an invasive procedure.