How is protamine sulfate dosed in a patient requiring reversal of unfractionated heparin?

By William Aird

  • Dose calculated based on the dose of heparin administered and the elapsed time since the last heparin dose.
  • 1 mg protamine sulfate IV neutralizes about 100 units of unfractionated heparin (UFH) given in past 2-3 hours (for example, protamine sulfate 25-35 mg would be administered in a patient receiving 1,000-1,250 units/hour UFH).
  • Given slowly over 10 minutes at a rate not to exceed 5 mg/minute.
  • Dose should not exceed 50 mg. When given at high dose, protamine sulfate can cause severe hypotension, cardiovascular collapse, noncardiogenic pulmonary edema, catastrophic pulmonary vasoconstriction, and pulmonary hypertension

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