ADD-ONS / MEDICATION / ANTICOAGULANT THERAPY
Unfractionated Heparin (UFH)
Created 03/02/2022, last revision 21/01/2023
- native heparin is a polymer with a molecular weight ranging from 3 to 30 kDa, although the average molecular weight of most commercial heparin preparations is in the range of 12 to 15 kDa
- while low molecular weight heparin ranges from 3 to 6 kDa
- it acts as an anticoagulant, preventing the formation of clots and extension of existing clots within the blood
Pharmacodynamics
- heparin acts as an anticoagulant by activating antithrombin III (AT III)
- AT III is an α2-globulin synthesized in the liver
- it inhibits thrombin and other factors (IX, X, XI, and XII ), which reduces the conversion of fibrinogen to fibrin
- heparin augments AT III activity by about 1,000 times
- heparin has no effect in the absence of AT III and has no fibrinolytic activity
- heparin further:
- releases lipoprotein lipase from the endothelium, which determines its antilipidemic effect
- reduces platelet adhesion to endothelium and release of the platelet-derived growth factor
- has a mild antihistamine effect

Pharmacokinetics
- the onset of the effect:
- IV – immediate
- SC – within 20-30 min
- the biological half-life is approximately 1-2 h (longer at higher doses); therefore, continuous infusion is preferable to intermittent IV administration
- after SC administration, peak plasma levels are reached in 2-4 h
- heparin binds to plasma proteins, some of which (particularly in inflammatory or tumor diseases) neutralize its anticoagulant activity
- biotransformation: liver and RES
- heparin is excreted in the urine and is not dialyzable
- heparin does not cross the placental barrier and does not pass into breast milk
Contraindications
- common contraindication like increased risk of bleeding (especially in people with uncontrolled blood pressure, liver disease, and stroke)
- HIT in patient´s personal history
Dosing and monitoring
Miniheparinisation (prophylactic dose)
- HEPARIN (1 amp=25000 IU/5ml) : 5000 units SC q8-12hr
- no significant differences in the incidence of pulmonary embolism or deep vein thrombosis were observed between the two types of heparin dosing (Reynolds, 2019)
- monitoring of the effect is not necessary
- in TEN prophylaxis, heparin is usually replaced by LMWH
- occurrence of HIT is lower in patients receiving LMWH compared to UFH (Junqueira, 2017)
Full dose heparin (therapeutic dose)
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Adverse events
- bleeding complications → neutralizing the effect of heparin
- heparin-induced thrombocytopenia (HIT)
- osteoporosis (long-term, high-dose treatment)
- allergic reactions
- hyperkalemia, hyperaldosteronism
- injection site ulcer (after deep SC injection)
- increased liver aminotransferase
- delayed transient alopecia
- rebound hyperlipemia on discontinuation of heparin
- vasospastic reactions (including episodes of painful, ischemic, and cyanosed limbs)