Aminocaproic Acid

Overview

Aminocaproic acid (epsilon aminocaproic acid; Amicar®) is a synthetic antifibrinolytic agent used in dogs as a hemostatic drug to help stabilize formed clots and reduce excessive bleeding associated with hyperfibrinolysis.

In small animal practice, its primary role is as an adjunctive therapy for conditions characterized by increased fibrinolytic activity, including delayed postoperative bleeding, particularly in greyhounds and other sighthound breeds. It has also been investigated for use in other bleeding disorders in dogs, although clinical efficacy varies depending on the underlying cause of hemorrhage.

Aminocaproic acid acts by inhibiting fibrinolysis rather than promoting clot formation, making correct patient selection and confirmation of hyperfibrinolysis essential prior to use. The drug is available in oral and injectable formulations, and injectable solutions may be administered orally in dogs with similar pharmacologic effects.

Indications

Aminocaproic acid is used in dogs as an antifibrinolytic agent in clinical situations where excessive clot breakdown contributes to active or delayed bleeding. Its use should be based on evidence or strong suspicion of hyperfibrinolysis.

• Delayed postoperative bleeding: Commonly used as prophylaxis to reduce delayed-onset hemorrhage following surgery, particularly in greyhounds and other sighthound breeds that are predisposed to postoperative bleeding.
• Hyperfibrinolysis-associated bleeding: Used to stabilize clots and reduce bleeding in dogs with confirmed or suspected hyperfibrinolysis, ideally diagnosed using thromboelastography (TEG) or similar coagulation testing.
• Active hemorrhage (adjunctive therapy): May be administered to dogs with active bleeding related to neoplastic disease, postsurgical complications, or other causes when hyperfibrinolysis is suspected to play a role.
• Pericardial effusion–associated bleeding: Has been used in dogs with hemorrhagic pericardial effusion secondary to cardiac masses, although clinical benefit is inconsistent.
• Degenerative myelopathy (investigational use): Historically used as an adjunctive treatment in dogs with degenerative myelopathy; however, controlled studies have not demonstrated clear clinical benefit, and disease progression is typically unaffected.

Dosage (Reference)

Dog

In dogs, aminocaproic acid is used extra-label as an antifibrinolytic agent. Dosing requirements in dogs may be higher than those extrapolated from human medicine, and dosage should be guided by the clinical scenario and, when available, coagulation testing such as thromboelastography (TEG).

Cat

Specific dosage recommendations for aminocaproic acid in cats are not provided in the available veterinary literature source. Safety, efficacy, and appropriate dosing have not been established.

Warnings & Precautions

Aminocaproic acid is a potent antifibrinolytic agent, and inappropriate use can increase the risk of serious thrombotic complications. Careful patient selection and monitoring are essential, particularly in dogs, before and during therapy.

• Disseminated intravascular coagulation (DIC): Contraindicated in dogs with active intravascular clotting, especially DIC, as inhibition of fibrinolysis may lead to fatal thrombus formation.
• Confirmation of hyperfibrinolysis: Do not administer in the absence of laboratory evidence of hyperfibrinolysis (e.g., thromboelastography), as inappropriate use may worsen outcomes.
• Urinary tract bleeding: Use cautiously in dogs with upper urinary tract hemorrhage, as clot formation in the renal pelvis or ureters may occur.
• Renal impairment: The drug is primarily eliminated by the kidneys; dose reduction and close monitoring are recommended in dogs with decreased renal function.
• Cardiac and hepatic disease: Use only when the potential benefits outweigh the risks, as altered drug handling or increased adverse effects may occur.
• IV administration: Rapid intravenous administration of undiluted aminocaproic acid may cause hypotension and bradycardia; IV doses should be given slowly and appropriately diluted.
• Electrolyte disturbances: Hyperkalemia has been reported, particularly in dogs with underlying renal disease; monitor serum electrolytes when indicated.
• Degenerative myelopathy: Use for this condition is considered investigational in dogs, with no proven clinical benefit; clients should be counseled accordingly.
• Cats: Safety and efficacy data are lacking for cats; use is not recommended without specialist oversight and careful risk–benefit assessment.

Drug Interactions

Aminocaproic acid has a limited number of clinically significant drug interactions; however, combinations that enhance coagulation may increase the risk of thrombosis and should be used cautiously in dogs. Data regarding drug interactions in cats are lacking.

• Blood products and procoagulant therapies: Concurrent administration with factor IX complex concentrates or anti-inhibitor coagulant products may increase the risk of pathologic thrombosis and should be avoided unless clearly indicated.
• Other antifibrinolytic or prothrombotic agents: Combined use may excessively suppress fibrinolysis and increase the risk of intravascular clot formation; careful risk–benefit assessment is required.

Side Effects & Overdose

Side Effects

Aminocaproic acid is generally well tolerated in dogs when used appropriately; adverse effects are infrequent and usually mild. Data regarding adverse effects in cats are limited.

• Gastrointestinal irritation: Occurs infrequently in dogs (≈1%); may include vomiting, diarrhea, or decreased appetite.
• Electrolyte disturbances: Hyperkalemia may develop, particularly in dogs with underlying renal impairment; serum electrolytes should be monitored when risk factors are present.
• Cardiovascular effects (IV use): Rapid intravenous administration may cause hypotension and bradycardia; administer IV doses slowly and diluted.
• Muscle effects: Rarely, muscle weakness or myositis has been reported in other species; if suspected in dogs, consider discontinuation and further evaluation.
• Cats: Adverse effect profile has not been established; use is not recommended without specialist guidance.

Overdose

Information on aminocaproic acid overdose in veterinary patients is limited. Toxicity is more likely with excessive intravenous dosing.

• Dogs: The reported IV lethal dose is approximately 2.3 g/kg. At lower overdose levels, tonic–clonic seizures have been observed.
• Neurologic signs: Seizures and CNS excitation may occur following significant overdose.
• No specific antidote: Treatment is supportive; aminocaproic acid is dialyzable.
• Management: Discontinue the drug, provide supportive care, and manage seizures if present. Consultation with a 24-hour veterinary poison center is strongly recommended.
• Cats: Overdose data are not available; avoid use due to unknown safety margins.

Key Notes

Practical clinical considerations to optimize the safe and appropriate use of aminocaproic acid in dogs and cats:

• Indication-specific use: Aminocaproic acid should be reserved for cases with documented or strongly suspected hyperfibrinolysis; routine use in undifferentiated bleeding disorders is not recommended.
• Laboratory confirmation: Whenever possible, diagnosis of hyperfibrinolysis should be supported by thromboelastography (TEG) before initiating therapy.
• Species differences: Most clinical experience and published data are in dogs; use in cats is poorly described and should be approached cautiously.
• Postoperative bleeding: Particularly considered in greyhounds and other sighthounds with delayed-onset postoperative hemorrhage.
• Administration flexibility: Injectable formulations may be administered orally in dogs with similar pharmacologic effects, allowing dosing flexibility when tablets are not available.
• Renal considerations: Dose adjustments or increased monitoring may be required in dogs with impaired renal function due to renal elimination of the drug.
• Limited evidence base: Clinical benefit in some conditions (e.g., degenerative myelopathy) remains unproven; expectations should be discussed clearly with owners.
• Short half-life: Frequent dosing schedules may be required to maintain antifibrinolytic effects.
• Adjunctive role: Aminocaproic acid does not replace definitive treatment of the underlying cause of bleeding and should be used as part of a broader management plan.