Protamine
Chemical
Protamine is a purified mixture of low molecular weight cationic (+) proteins prepared from salmon sperm
Use
Neutralise anticoag effects of heparin
Presentation
Clear, colourless solution
10mg/mL protamine sulphate
Route / Dose
Slow IV injection
1mg for every 100 units heparin (max 50mg in 10 mins)
Determined by activated clotting time
MoA (mechanism)
- Positively charged alkaline protamine complexes bin to the negatively charged acidic heparin to form stable complex devoid of any anticoagulant activity
NB: at high doses, heparin can interact with platelets & protein including fibrinogen → cause anticoagulation due to inhibition of formation of THROMBOPLASTIN
Adverse Effects
CVS
- Histamine release → VD, flushing, hypotension
- -ve inotropy
- with rapid IV bolus
RESP
- Pulmonary HTN (complement activation → R) HF → death/arrest)
ALLERGY
- Anaphylaxis common in diabetics → brain, liver, ↓BP, bronchospasm, angioedema
“Heparin Rebound”
- Rapid clearance of complexes by RES → free heparin to anticoagulated
Drug interactions
- Incompatible with antibiotics inc. cephalosporins & penicillins