Indications
Protamine Sulfate is used to reverse (neutralise) the blood-thinning effect of Heparin. It is used after heart surgery, dialysis or other procedures where Heparin was given, and to treat bleeding or Heparin overdose. It only partly reverses low molecular weight heparins such as Enoxaparin.
How It Works
Protamine is a small protein with a strong positive charge. Heparin has a strong negative charge. When they meet in the blood, they bind tightly together to form a stable, inactive complex, so Heparin can no longer stop the blood from clotting. The effect starts within about 5 minutes.
Dosage and Administration
It is given only by a doctor or nurse as a slow injection or infusion into a vein, in hospital, with monitoring of blood pressure, heart rate and clotting tests. The dose depends on how much Heparin was given and how long ago, and is worked out by the medical team. Giving it too fast can cause a sharp fall in blood pressure.
Interactions
It is used specifically to counteract Heparin. It does not reverse Warfarin, direct oral anticoagulants such as Rivaroxaban or Apixaban, or antiplatelet medicines. It can react with certain antibiotics, including some cephalosporins and penicillins, if mixed in the same line, so it is not mixed with other drugs.
Contraindications
- Known previous allergy or severe reaction to protamine
Side Effects
Possible effects include a sudden fall in blood pressure, slow heart rate, flushing, a feeling of warmth, nausea, vomiting, tiredness and breathlessness. Serious allergic reactions, a sudden rise in pressure in the lung blood vessels, and fluid in the lungs can occur. If too much is given, protamine itself can cause bleeding, and Heparin effect can sometimes return a few hours later (heparin rebound).
Tell the nurse or doctor at once if you feel faint, have chest tightness, wheezing, difficulty breathing, swelling of the face, a rash, or notice new bleeding during or after the injection; these need urgent treatment.
Pregnancy and Lactation
There is limited information on use in pregnancy and breastfeeding. It is used when the doctor decides the benefit outweighs any risk, as uncontrolled bleeding is dangerous for mother and baby.
Precautions and Warnings
The risk of a severe allergic reaction is higher in people with fish allergy, men who have had a vasectomy or are infertile, and people who have used insulin products containing protamine (such as NPH insulin) or had protamine before. Resuscitation equipment should be ready. Clotting tests are repeated after the dose.
Overdose
Too much protamine can itself thin the blood and cause bleeding, and may cause low blood pressure. The medical team will monitor clotting and give supportive treatment, including blood products if needed.
Therapeutic Class
Heparin antagonist (antidote)
Storage
Hospital medicine: store as directed on the pack, usually in a refrigerator at 2 to 8°C, do not freeze. Keep out of the reach of children.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.