BLACK BOX WARNING
- HIT can cause life-threatening thrombosis
heparin (unfractionated)
Brand: UFH, Hep-Lock
⚠ BBW ISMP High Alert TDM Required Prototype Drug
Drug Class: anticoagulant
Drug Family: anticoagulant
Subclass: unfractionated heparin
Organ Systems: cardiovascularhematology-oncology
Mechanism of Action
Binds antithrombin III causing conformational change that accelerates AT-III inhibition of thrombin (IIa) and factor Xa.
antithrombin IIIfactors IIa and Xa
Indications
- DVT/PE treatment
- ACS
- surgical thromboprophylaxis
- hemodialysis
- bridging to warfarin
Contraindications
- HIT (heparin-induced thrombocytopenia) history
- active uncontrolled bleeding
- severe thrombocytopenia
Adverse Effects
Common
- bleeding
- thrombocytopenia
- injection site reactions
Serious
- HIT type II with paradoxical thrombosis
- major hemorrhage
- osteoporosis (long-term)
Pharmacokinetics (ADME)
| Absorption | IV or SC only |
| Distribution | does not cross placenta |
| Metabolism | reticuloendothelial system |
| Excretion | renal |
| Half-life | 1-5 hours (dose-dependent) |
| Onset | immediate IV |
| Peak | 2-4 hours SC |
| Duration | variable |
| Protein Binding | extensive |
| Vd | variable |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| NSAIDs/antiplatelet agents | increased bleeding risk | major |
| protamine sulfate | reversal agent | beneficial |
Nursing Considerations
- Weight-based dosing: 80 units/kg bolus then 18 units/kg/hr; adjust by aPTT (target 60-100 sec)
- Monitor platelets every 2-4 days days 4-14 (HIT window); >50% drop = stop heparin
- HIT: stop heparin immediately; use direct thrombin inhibitor (argatroban or bivalirudin)
- Antidote: protamine sulfate 1 mg per 100 units heparin given in last 2-3 hours
- Safe in pregnancy (does not cross placenta)
Clinical Pearls
- HIT type II: antibodies to heparin-PF4 complex cause platelet activation and thrombosis despite thrombocytopenia
- Protamine reversal: positively-charged protamine binds negatively-charged heparin
- Weight-based dosing nomogram reduces time outside therapeutic range
Safety Profile
Pregnancy safe
Lactation use-with-caution
Renal Adjustment Required
Hepatic Adjustment Not required
TDM Required
Concordance Terms
Cross-referenced clinical concepts — click any term to see all content where it appears.