Indications
Protamine Sulphate is an injection used to reverse (neutralise) the blood-thinning effect of Heparin. It is used at the end of heart surgery, dialysis or other procedures where Heparin was given, and to treat bleeding or overdose caused by Heparin. It partly reverses low molecular weight heparins such as Enoxaparin. It is used only in hospital.
How It Works
Protamine is a protein with a strong positive charge. Heparin has a strong negative charge. When they meet in the blood, they bind tightly to form a stable inactive complex, so Heparin can no longer stop blood from clotting. The effect starts within about 5 minutes.
Dosage and Administration
It is given by a doctor or nurse as a slow injection or infusion into a vein, usually over about 10 minutes. The dose is calculated from the amount of Heparin given and the time since it was given, and is checked with blood clotting tests. Giving it too fast can cause a sudden drop in blood pressure, so it is always given slowly with monitoring.
Interactions
Protamine is incompatible with some antibiotics, such as certain penicillins and cephalosporins, in the same syringe or line. People who have received protamine-containing insulin (such as NPH or isophane insulin) have a higher risk of allergic reactions to it. In excess, protamine itself has a mild anticoagulant effect.
Contraindications
- Known severe allergy to Protamine.
- Extra caution (not absolute) in people with fish allergy, previous vasectomy or infertile men, and those who have used protamine-containing insulin, because they are more likely to react.
Side Effects
Possible effects include flushing and a feeling of warmth, low blood pressure, slow heartbeat, nausea, vomiting, tiredness and shortness of breath. Serious reactions such as severe allergy (anaphylaxis), a sudden rise of pressure in the lung arteries, bronchospasm and circulatory collapse can occur, which is why it is given slowly in a monitored setting. Bleeding may return a few hours later (heparin rebound).
Tell the doctor or nurse immediately if you feel wheezy, short of breath, dizzy, have chest tightness, itching, swelling of the face, or if bleeding starts again after the injection.
Pregnancy and Lactation
There is little information on use in pregnancy and breastfeeding. Because it is used to treat urgent, potentially life-threatening bleeding, the doctor will give it when the benefit outweighs the risk.
Precautions and Warnings
Resuscitation equipment must be available. Clotting tests are monitored after the dose, and repeat doses may be needed, especially after large Heparin doses or in heart surgery. Too much Protamine can itself cause bleeding, so the dose must not exceed what is needed.
Overdose
Overdose may cause bleeding, low blood pressure and breathing problems. Treatment is supportive and given by the hospital team.
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.