Makindo Medical Notes.com

There are two main types - unfractionated (UFH) and low molecular weight Heparin (LMWH)

About: Always check the BNF or equivalent for prescribing advice

• Used both in treatment and prevention of thrombosis
• Binds to antithrombin and enhances inactivation of factor Xa

Details

• Produced from enzyme action or breakdown of normal Heparin
• More predictable than UFH and can be given in a weight-adjusted dose.
• Action is against Factor Xa
• Renally excreted so dose reduced in renal disease

Actions

• Works by binding Factor X - a more predictable effect
• Only given by subcutaneous injection
• Cannot be reversed by protamine

Cautions

• Thrombocytopenia, haemophilias, liver failure, renal failure
• Systolic >200 mm Hg or diastolic >120 mm Hg
• Active peptic ulcer, oesophageal varices
• Aneurysm, proliferative retinopathy, recent organ biopsy
• Recent trauma or surgery to head, orbit, spine, recent stroke
• Confirmed intracranial or intraspinal bleed
• History of Heparin-induced thrombocytopenia or thrombosis

Monitoring

• Monitoring if there are complications such as haemorrhage, an extension of thrombosis, or accidental overdose; and in patients with renal failure.
• Plasma anti-Xa assays activity
• Not usually needed except in renal failure
• Monitoring of the platelet count to detect Heparin-induced thrombocytopenia

Formulations

• Tinzaparin, Enoxaparin (US Lovenox), Fondaparinux

Side effects

• Bleeding, Hyperkalaemia, Thrombocytopenia
• Osteoporosis with long term use > 20 weeks
• Heparins induced thrombocytopenia (HIT). Seen in 5% which is more common the longer treatment duration. Stop drug and seek haematology advice.