Heparin antagonist
Protamine sulfate
Adult dose
Dose: Heparin reversal: 1mg per 100 units heparin given in last 15 min (max 50mg). LMWH (within 8h): 1mg per 1mg enoxaparin (partial)
Route: IV slow
Frequency: single (titrate to APTT)
Clinical pearls
- Reversal of unfractionated heparin (full); LMWH (partial); after CPB
- Slow IV (≤5 mg/min) to minimise hypotension
Contraindications
- Hypersensitivity to fish/protamine
Side effects
- Hypotension
- Bradycardia
- Pulmonary hypertension
- Anaphylaxis (esp. previous exposure, NPH insulin users, fish allergy)
- Bleeding (if excess dose — paradoxical anticoagulant)
Interactions
- Heparin (specific)
Monitoring
- APTT
- BP
- HR
Reference: BNF; AAGBI; UK guidelines; https://bnf.nice.org.uk/drugs/protamine-sulfate/. Verify against your local formulary and the latest BNF before prescribing.
Related
Curated clinical cross-links plus same-class fallbacks.
Calculators
Pathways
- New-Onset Atrial Fibrillation · ESC 2020 AF Guidelines; NICE NG196
- Hypertensive Emergency · ESC/ESH 2018 Hypertension Guidelines; NICE NG136
- Bradycardia Management · Resuscitation Council UK ABCDE; ESC 2021 Pacing Guidelines
- Ventricular Tachycardia / Fibrillation · Resuscitation Council UK ACLS; ESC 2022 Ventricular Arrhythmia Guidelines
- Syncope Assessment · ESC 2018 Syncope Guidelines; NICE NG109
- Acute Chest Pain · NICE CG95; ESC 2023 ACS Guidelines