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Protamine Sulfate

Prescription
Heparin Antagonist
Last reviewed 21 Apr 2026 · PetCare.AI Editorial Team
Species
Dog, Cat
Brands
1 available
Interactions
1 documented
Formulations
1

Mechanism of action

Positively charged protein derived from salmon sperm that binds ionically to negatively charged heparin molecules, forming a stable heparin-protamine complex that is pharmacologically inactive, reversing heparin anticoagulation within minutes.

At a glance

Class
Heparin Antagonist
Schedule
Prescription
Storage
Refrigerate 2–8°C; stable 24h at room temperature after withdrawal from vial

Dosing

🐕

Dog

Only for reversing unfractionated heparin overdose or post-procedural hepariniza
Dose
Route
PO
Frequency
Single dose; may repeat 50% dose if aPTT still prolonged after 30 min
🐈

Cat

Rarely needed in clinical feline practice
Dose
Route
IV
Frequency
Single dose
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

Formulations

💊

Other — 1

Strength

Storage

Refrigerate 2–8°C; stable 24h at room temperature after withdrawal from vial

Safety

Monitoring parameters

aPTT or ACT before and 15 min post-administrationBlood pressure (continuous during infusion)Signs of hypersensitivity for 30 min
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

Interactions

Moderate — 1

Enoxaparin
moderate
Protamine only partially reverses LMWH (~60% of anti-Xa activity neutralized, vs 100% for unfractionated heparin). Incomplete reversal.
Management: Give protamine 1 mg per 100 anti-Xa units of enoxaparin. Expect only partial reversal. May need repeat dosing. Monitor anti-Xa activity.
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

Brands

Other markets

Protamine Sulfate Injection

FAQs

Frequently asked questions

What is Protamine Sulfate?
Protamine Sulfate is a heparin antagonist used in pets. Positively charged protein derived from salmon sperm that binds ionically to negatively charged heparin molecules, forming a stable heparin-protamine complex that is pharmacologically inactive, reversing heparin anticoagulation within minutes.
What is Protamine Sulfate used for in pets?
Protamine Sulfate is used in veterinary medicine for: Only for reversing unfractionated heparin overdose or post-procedural hepariniza; Rarely needed in clinical feline practice.
What is the Protamine Sulfate dose for dogs?
For dogs, Protamine Sulfate is typically dosed as follows — Only for reversing unfractionated heparin overdose or post-procedural hepariniza: undefined undefined PO Single dose; may repeat 50% dose if aPTT still prolonged after 30 min. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
What is the Protamine Sulfate dose for cats?
For cats, Protamine Sulfate is typically dosed as follows — Rarely needed in clinical feline practice: undefined undefined IV Single dose. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
Does Protamine Sulfate need a prescription?
Yes. Protamine Sulfate is a prescription medication and should only be administered under veterinary supervision.
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

References

References

The PetCare.AI drug reference is built from 13 authoritative sources cited across 580 drug monographs.

Textbooks & handbooks — 5

  • Plumb's Veterinary Drug Handbook
  • Withrow & MacEwen's Small Animal Clinical Oncology
  • Merck Veterinary Manual
  • NRC Nutrient Requirements of Dogs and Cats
  • Veterinary Pharmacology and Therapeutics (Riviere & Papich)

Clinical guidelines & consensus — 4

  • ASPCA Animal Poison Control Center Guidelines
  • AAHA Diabetes Management Guidelines
  • ASPCA Poison Control Guidelines
  • RECOVER CPR Guidelines

Journals & peer-reviewed studies — 2

  • EPIC Study (J Vet Intern Med 2016)
  • JVIM FAT CAT Study

Regulatory & approvals — 1

  • CDSCO Veterinary Drug Approval Registry (1969–2026)

Databases — 1

  • Washington State University VCPL MDR1 Database
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