Heparin therapy.

Unfractionated heparin (UFH) therapy is most commonly administered with an initial IV bolus of 80 units/kg or 5000 units. Weight-based UFH dosages have been shown to be more effective than standard fixed boluses in rapidly achieving therapeutic levels. The initial bolus is followed by a continuous IV drip, initially at 18 units/kg per hour or 1300 units per hour. The half-life of IV UFH ranges from 45 to 90 minutes and is dose dependent. 
Post heparin therapy aPTT should be monitored.

The level of antithrombotic therapy after giving heparin should be monitored every 6 hours using the activated partial thromboplastin time (aPTT), with the goal range of 1.5 to 2.5 times control values.

This should correspond with plasma heparin anti-Xa activity levels of 0.3 to 0.7 IU/mL.