Aminocaproic Acid
Amicar
Antifibrinolytic (lysine analogue)
Binds plasminogen lysine-binding sites → blocks plasmin formation → stabilizes clot. Same mechanism as TXA (~10× less potent).
Indications
- •Fibrinolytic bleeding (cardiac surgery, hyperfibrinolysis)
- •Prophylaxis in high-bleeding surgery
- •Mucosal bleeding
Dosing
| Context | Adult | Pediatric |
|---|---|---|
| Loading | 4–5 g IV over 1 h, then 1 g/hr infusion | — |
| Cardiac surgery | Institution protocol (e.g., 100–150 mg/kg load) | — |
Pharmacokinetics
Onset ~1 h. Half-life ~2 h. Renally cleared.
Side effects
- !Thrombosis (theoretical)
- !Hypotension with rapid infusion
- !Myopathy (prolonged use)
- !Do not use in DIC without control
Contraindications
- ×Active intravascular clotting/DIC
- ×Hematuria of upper-urinary-tract origin (ureteral clot obstruction)
Clinical pearls
- ★The 'other' antifibrinolytic — TXA is more potent and more commonly used; interchangeable in concept.
- ★Avoid in DIC and in upper-tract hematuria (clot colic/obstruction).
Other drugs in Coagulation Related
- Heparin (unfractionated)
Activates antithrombin → inactivates IIa (thrombin) and Xa.
- Tranexamic Acid (TXA)
Reversibly binds plasminogen, blocking conversion to plasmin → preserves fibrin clot.
- Protamine Sulfate
Strongly basic (positive-charge) protein binds to highly acidic (negative-charge) heparin → inactive ionic complex → renal excretion. 1 mg protamine neutralizes ~100 units heparin.
- DDAVP (Desmopressin)
Selective V2 agonist (renal water retention + Factor VIII/vWF release from endothelial Weibel-Palade bodies). NO V1 vasopressor activity at therapeutic dose.
- Warfarin
Inhibits vitamin K epoxide reductase (VKORC1) → depletes reduced vitamin K → ↓ synthesis of factors II, VII, IX, X and proteins C/S. Full effect takes days (waits for existing factor decay).
- Enoxaparin
Antithrombin-mediated inhibition, weighted toward factor Xa over IIa (~3.8:1). More predictable than UFH — no routine monitoring.
- Dalteparin
Antithrombin-mediated factor Xa > IIa inhibition. Similar profile to enoxaparin; preferred LMWH in cancer-associated VTE (CLOT trial).
Suggested reading
- •Miller's Anesthesia, 9e
- •FDA package insert
