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Pharmacology · Antifibrinolytic haemostatics

Aminocaproic acid !

An older lysine analogue antifibrinolytic used when excessive fibrinolysis causes bleeding, such as after heart or prostate surgery.

Updated 2026-11-01

Also called: epsilon-aminocaproic acid (EACA)

The figure shows epsilon-aminocaproic acid (6-aminohexanoic acid) bound to kringle 4 of human plasminogen.

Target in 3D: Lysine-binding sites (kringle domains) of plasminogen. PDB structure 2PK4 (RCSB PDB, public domain). View the structure at RCSB PDB

Mechanism of action

Like tranexamic acid, it is a lysine analogue that competes for the lysine-binding sites of plasminogen and plasmin. It mainly inhibits plasminogen activation and, to a lesser degree, plasmin itself, so fibrin is not digested.

  1. Plasminogen binds fibrin through its lysine-binding sites
  2. The drug, a lysine analogue, occupies those sites
  3. Plasminogen and plasmin cannot attach to fibrin
  4. The clot is protected from early breakdown

Pharmacokinetics

Absorption
Absorbed rapidly by mouth; also given intravenously
Elimination
Kidneys, mostly unchanged
Half-life
About 2 hours

Indications

  • Bleeding when fibrinolysis contributes, e.g. after cardiac or prostatic surgery
  • Haemophilia, to reduce bleeding after tooth extraction Haemophilia A and B →

Adverse effects

Common

  • Nausea, abdominal cramps, diarrhoea
  • Dizziness, headache
  • Hypotension with rapid intravenous injection

Contraindications

  • Active intravascular clotting; disseminated intravascular coagulation unless heparin is given too
  • Haematuria from the upper urinary tract (unless the benefit clearly outweighs the risk)

Key interactions

Pro-thrombotic products (factor IX complex concentrates, hormonal contraceptives)
Possible additive risk of thrombosis

What is monitored

  • Creatine kinase (CK) during long courses; stopped if it rises
  • Blood pressure and heart rhythm during infusion
  • Urine output and kidney function

Administration and safety

  • Rapid intravenous injection is avoided because it can cause hypotension, bradycardia and arrhythmias
  • Used only when laboratory findings show hyperfibrinolysis; it is not a treatment for DIC

Nursing care

  • Monitor blood pressure and heart rate during the infusion
  • Ask about muscle pain or weakness and dark urine
  • Watch for signs of thrombosis and reduced urine output

Pregnancy and breastfeeding

Human data are limited; it is used in pregnancy only if clearly needed (for example, bleeding from placental abruption).

Test yourself

Think of the answer, then tap the question to see it.

What muscle toxicity can prolonged use cause?

Myopathy with necrosis and rhabdomyolysis; CK is monitored.

Why must DIC be distinguished from primary fibrinolysis before using it?

In DIC, blocking fibrinolysis without heparin can worsen intravascular clotting.

What happens with fast intravenous injection?

Hypotension, bradycardia or arrhythmias.

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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: DailyMed - AMINOCAPROIC ACID injection, solution (DailyMed (U.S. National Library of Medicine), 2026); Aminocaproic Acid: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2023); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 36 (McGraw Hill, 2023); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.