Diabetic patients treated with NPH (isophane) insulin — insulin bound to protamine — have an increased risk of severe anaphylactic reactions to IV protamine given as a heparin antidote.
NPH insulin is an insulin-protamine suspension (Prontuário 8.4.1); prior exposure generates anti-protamine antibodies; IV protamine can cause severe hypotension and anaphylaxis (Prontuário 4.3.1.1: "anaphylactic reactions in diabetic patients who received protamine zinc insulin"; EMC Prosulf 4.4).
Anaphylaxis signs (sudden hypotension, bronchospasm, urticaria) during infusion; aPTT/ACT.
Sudden blood pressure drop, breathing difficulty, cardiovascular collapse.
ALWAYS ask about NPH/protamine-zinc insulin exposure before IV protamine; slow infusion (≤ 5 mg/min, max 50 mg/dose) with resuscitation team available; consider alternatives (heparin withholding, bexatra).
EMC-UK — Prosulf (Protamine Sulfate) 10mg/ml SmPC [Wockhardt], sec. 4.2/4.4: https://www.medicines.org.uk/emc/product/8/smpc; INFARMED Prontuário Terapêutico (11th ed., 2012), 4.3.1.1 Heparins: anaphylactic reactions in diabetics on protamine zinc insulin; DailyMed — Protamine Sulfate Injection label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=c76876da-b9a8-45d0-9278-7df3288d3a06
No documented food or drink interactions.
Protamine causes severe hypotension and reduced cardiac output — caution in decompensated heart failure.
Administer slowly (≤ 50 mg/10 min) with continuous haemodynamic monitoring.
Prontuário Terapêutico INFARMED, 4.3.1.1: "Protamine may rarely cause anaphylactic reactions..." and "severe hypotension"; EMC-UK Prosulf SmPC § 4.2/4.4.
No entry in the Prontuário annexes; protamine is the antidote for heparin (1 mg per 100 IU of heparin), given IV in emergency settings (over-anticoagulation, reversal in cardiac surgery). The decision to use is driven by maternal benefit; heparin does not cross the placenta, so transient fetal hypocoagulability is rarely relevant.
Emergency IV use as maternal benefit dictates; excessive doses cause hypotension and protamine's own anticoagulant effects.
Compatible as an emergency antidote — degraded protein; no reports of effects on the infant.
Prontuário Terapêutico INFARMED — 8.6 (Anticoagulants): reversal with protamine sulphate (l. 18121-24). EMC-UK (MHRA) — Protamine Sulphate SmPC.
Clinical and educational support tool. The information does not replace a medical prescription or the opinion of a qualified healthcare professional.
Heparin neutralisation within 30–60 s (1 mg neutralises ~ 100 U); partial LMWH reversal.
Cationic polypeptide ionically binding the acidic sulphate group of heparin, forming a stable complex without anticoagulant activity. Patients previously exposed to protamine (NPH or protamine-zinc insulins) carry pre-formed antibodies that can mediate anaphylactic reactions on IV re-exposure — hence the mandatory history-taking before administration.
IV exclusive; immediate action.
Peptidase degradation; metabolism not fully elucidated; renal excretion.
~ 7–9 min (clinical effect ~ 2 h).
Medicines from the same therapeutic group (ATC classification) or the same pharmacological class.
