Dalteparin (Orthopaedic VTE Prophylaxis)

How it works

It potentiates antithrombin, producing preferential inhibition of factor Xa over thrombin to reduce thrombin generation and clot formation.

Prescribing in practice

• Bleeding is the main hazard and the agent is contraindicated in active major bleeding — assess bleeding risk against thrombotic risk, time perioperative doses carefully, and take special care with neuraxial anaesthesia because of the risk of spinal/epidural haematoma.
• It can cause heparin-induced thrombocytopenia and hyperkalaemia, so monitor platelets where indicated and use caution in renal impairment where accumulation increases bleeding risk.
• Dose is weight-based and follows local VTE prophylaxis protocols; protamine only partially reverses its effect, and the SPC guides timing around surgery and regional blocks.

Monitoring

Monitor for bleeding, and check platelet count and potassium where indicated, with renal function review in those at risk of accumulation.

Counselling the patient

• Report unusual bruising or bleeding, and any back pain, leg weakness or numbness after a spinal injection or epidural.
• Injection-site bruising is common; rotate sites if self-administering.
• Keep taking it for the full recommended period after surgery to prevent clots, alongside mobilisation.

Evidence & guidelines

NICE VTE prevention guidance recommends low-molecular-weight heparin such as dalteparin as a pharmacological prophylaxis option after major orthopaedic surgery.