Class: Antiheparin Agents
CAS Number: 9009-65-8
Possible severe hypotension, cardiovascular collapse, noncardiogenic pulmonary edema, catastrophic pulmonary vasoconstriction, and pulmonary hypertension with rapid IV injection, high doses, repeated doses, or previous exposure to protamine or protamine-containing drugs (e.g., insulin).100 Other possible risk factors include known sensitivity to fish, vasectomy, severe left ventricular dysfunction, and abnormal pulmonary hemodynamics.100 Weigh risk against anticipated benefit of protamine therapy in patients with risk factors.100 Administer only when facilities and equipment for treatment of such reactions are readily available.100 (See Sensitivity Reactions under Cautions.)
Protamine should not be used for bleeding that occurs without prior exposure to heparin.100
Heparin antagonist; prepared from the sperm or mature testes of salmon or related species.100
Uses for Protamine Sulfate
Treatment of severe heparin overdosage.100 116
Do not use for minor bleeding during heparin therapy.123 (See Boxed Warning.) Heparin withdrawal usually corrects minor overdosage or bleeding within a few hours.123
Heparin Neutralization during Extracorporeal Circulation
Neutralization of heparin administered during extracorporeal circulation† in arterial and cardiac surgery or dialysis procedures.100 122
Heparin Neutralization in Pregnant Women Near Delivery
Neutralization of anticoagulant effect of heparin to reduce risk of bleeding near delivery† in pregnant women receiving heparin therapy who go into spontaneous labor.125
Low Molecular Weight Heparin Overdosage
Has been used for treatment of low molecular weight (LMW) heparin (e.g., dalteparin, enoxaparin, tinzaparin [no longer commercially available in the US]) overdosage†.114 115 121 However, neutralization of an LMW heparin is not complete even with multiple doses of protamine.114 115 121 (See Actions.)
Protamine Sulfate Dosage and Administration
With severe heparin overdosage, discontinue heparin and administer protamine sulfate immediately.a Blood transfusions may be required for massive blood loss.100 a
Dose of protamine sulfate determined by dose of heparin received, route of administration, time elapsed since heparin was given, and blood coagulation studies.100 116 117 Generally, 1 mg of protamine sulfate will neutralize no less than 100 units of heparin sodium.100 117
Blood heparin concentrations decrease rapidly after IV administration of heparin; dose of protamine sulfate required in the treatment of IV heparin overdosage also decreases rapidly as time elapses.100
Monitor therapeutic response through coagulation studies (aPTT, activated coagulation time [ACT], heparin titration test with protamine, plasma thrombin time).100 117 a
Additional doses of protamine sulfate may be required in patients with heparin rebound (e.g., as may occur during extracorporeal circulation† in arterial and cardiac surgery or dialysis procedures) if indicated by coagulation studies.100 119 123 a (See Effects on Hemostasis under Cautions.)
Low Molecular Weight Heparin Overdosage†
Dose of protamine sulfate determined by dose of LMW heparin received, the time elapsed since the drug was given, and blood coagulation studies.114 115 121
Following higher doses of protamine sulfate, aPTT may remain more prolonged than would be the case following treatment of heparin overdosage since anti-factor Xa activity is never completely neutralized.114 115 A maximum of about 60–75% or 60% of anti-factor Xa activity is neutralized with protamine sulfate administration for overdosage of dalteparin or enoxaparin, respectively.114 115
For solution and drug compatibility information, see Compatibility under Stability.
Administer by very slow IV injection.100 (See Sensitivity Reactions under Cautions.)
Has been administered by continuous IV infusion†.117
May be administered without further dilution at a concentration of 10 mg/mL.100 However, if more dilute infusion solution is desired, further dilution in 5% dextrose or 0.9% sodium chloride injection recommended.100 Contains no preservatives; discard unused portion.100
Rate of Administration
Administer by very slow IV injection over 10 minutes.100 116
Available as protamine sulfate; dosage expressed in terms of the salt.100
Severe bleeding occurring a few minutes after IV injection of heparin: 1 mg for every 100 units of heparin sodium administered.100 116 117
Severe bleeding occurring 30 minutes after IV injection of heparin: 0.5 mg for every 100 units of heparin sodium administered.100
Severe bleeding occurring ≥2 hours after IV injection of heparin: 0.25–0.375 mg for every 100 units of heparin sodium administered.a
Severe bleeding occurring after sub-Q injection of heparin: Some clinicians recommend 1–1.5 mg for every 100 units of heparin sodium; prolonged infusion may be required to neutralize sub-Q heparin dose.a A loading dose of 25–50 mg by slow IV infusion suggested by some clinicians,a with remainder of calculated dose administered by continuous IV infusion† over 8–16 hours or expected duration of absorption of heparin.a
Heparin Neutralization During Extracorporeal Circulation†
1.5 mg for every 100 units of heparin sodium administered.a Alternatively, determine dosage by using sequential ACT determinations and a dose-response curve which correlates results with amount of heparin remaining in body.a
Low Molecular Weight Heparin Overdosage†
Severe bleeding within 8 hours of administration of an LMW heparin: 1 mg for every 100 anti-factor Xa units of LMW heparin (e.g., enoxaparin sodium, dalteparin sodium, tinzaparin sodium) administered (e.g., 1 mg of enoxaparin sodium has an anti-factor Xa activity of approximately 100 units).114 115 117 If aPTT measured 2–4 hours after first infusion of protamine sulfate remains prolonged or if bleeding continues, may administer a second dose of 0.5 mg protamine sulfate for every 100 anti-factor Xa units of LMW heparin administered.114 115 117 121
Severe bleeding >8 hours after administration of an LMW heparin: 0.5 mg for every 100 anti-factor Xa units of LMW heparin administered.114 117
Protamine sulfate administration may not be required if >12 hours has elapsed since administration of enoxaparin.114
Maximum 50 mg administered in any 10-minute period, unless larger dose clearly needed.100 116 (See Sensitivity Reactions under Cautions.)
Cautions for Protamine Sulfate
Known hypersensitivity to protamine sulfate.100
Effects on Hemostasis
Heparin rebound (hyperheparinemia) with bleeding reported (e.g., after cardiac surgery, dialysis procedure).100 123
Heparin rebound usually occurs several hours after heparin has been adequately neutralized by protamine sulfate but has been reported 0.5–18 hours following cardiopulmonary bypass procedure†.100 123
Precise cause unknown; may result from release of heparin from protamine-heparin complex or from extravascular compartments.119 123 (See Metabolism under Pharmacokinetics.)
Monitor patients closely following cardiac surgery; administer additional doses of protamine sulfate if indicated by coagulation studies.100 117 119 123
Severe hypotension and potentially fatal anaphylactoid reactions reported, particularly with large doses or too-rapid administration.100 109 110 111 112 113 114 115 116 121 122 123 Take particular care to avoid overdosage with protamine.114 115 121 (See Boxed Warning.)
Patients at increased risk for development of antiprotamine antibodies and hypersensitivity reactions include infertile or vasectomized men,100 101 102 103 104 105 106 107 108 117 123 those with previous exposure to protamine-containing preparations (e.g., protamine-containing insulin, previous protamine sulfate therapy),10 100 109 110 112 113 or those with known hypersensitivity to fish.8 100 113
Severe reactions to IV protamine can occur in absence of local or systemic allergic reactions to sub-Q protamine-containing insulin.100 Fatal anaphylaxis reported in at least 1 patient with no prior history of allergies.100
Minimize these adverse effects by administering drug slowly.100 117 123 (See IV Administration under Dosage and Administration.) Administer only when medical facilities equipped to provide resuscitation and treat shock available.100 Patients at risk for protamine allergy can be pretreated with corticosteroids and antihistamines.117 (See Actions.)
Not known whether protamine sulfate is distributed into milk.100 Use caution.100
Safety and efficacy not established in children.100
Common Adverse Effects
Decreased BP or hypotension,100 117 123 bradycardia,100 117 skin reactions (e.g., flushing, feeling of warmth, urticaria, edema),120 123 dyspnea,100 nausea,100 vomiting,100 lassitude,100 back pain.100
Interactions for Protamine Sulfate
Neutralization of anticoagulant activity of heparin100 117 123
Prolongs absorption of insulin123
Incomplete neutralization of anticoagulant activity of LMW heparin114 115 117 121
Protamine Sulfate Pharmacokinetics
Neutralization of heparin occurs <5 minutes after IV administration.100
Variable duration presumably results from release of heparin from protamine-heparin complex or extravascular compartments.118 119 120 123 (See Metabolism under Pharmacokinetics.)
Not known whether protamine sulfate is distributed into milk.100 (See Lactation under Cautions.)
Metabolic fate of the protamine-heparin complex has not been elucidated; however, protamine-heparin complex may be partially metabolized or attacked by fibrinolysin, freeing heparin.100 (See Effects on Hemostasis under Cautions.)
Without heparin in healthy individuals: Median 7.4 minutes.117 118
Following cardiopulmonary bypass procedure† with heparin: Median 4.5 minutes.119
Solution for Injection
20–25°C; do not freeze.100
For information on systemic interactions resulting from concomitant use, see Interactions.
Incompatible with some anti-infective agents, including some cephalosporins and penicillins.100
Neutralization of anticoagulant activity of heparin by complexing with heparin to form a stable salt.100 117 123 124 Protamine-heparin complex has no anticoagulant activity.100 117 123 124
Does not bind to the low molecular weight fragments within LMW heparin preparations117 resulting in incomplete neutralization of anti-factor Xa activity when protamine is used to treat overdosage of LMW heparins.114 115 117 121
Has weak anticoagulant activity as a result of inhibition of platelet aggregation and interaction of many proteins, including fibrinogen,100 120 123 and inhibition of thromboplastin generation and activity, which prevents conversion of prothrombin to thrombin.a
Reduces systolic and diastolic BP, increases pulmonary artery pressure, and decreases heart rate and systemic vascular resistance.123 124
Vasoactive effects associated with release of vasoactive mediators (e.g., histamine, bradykinin, thromboxane, nitric oxide), complement activation, and antibody production.120 122 123
Advice to Patients
Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs and dietary or herbal supplements, as well as any concomitant illnesses.100
Importance of women informing their clinician if they are or plan to become pregnant or plan to breast-feed.100
Importance of informing patients of other important precautionary information.100 (See Cautions.)
Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.
Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.
Injection, for IV use only
Protamine Sulfate Injection (preservative-free; available as single-dose vials)
AHFS DI Essentials. © Copyright 2017, Selected Revisions June 19, 2015. American Society of Health-System Pharmacists, Inc., 4500 East-West Highway, Suite 900, Bethesda, Maryland 20814.
Only references cited for selected revisions after 1984 are available electronically.
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a. AHFS Drug Information 2010. McEvoy GK, ed. Protamine. Bethesda, MD: American Society of Health-System Pharmacists; 2010:1601-3.