What is the role of oral aminocaproic acid (ACA) in the treatment of hyphema?

Updated: Jan 18, 2019
  • Author: David L Nash, MD; Chief Editor: Andrew A Dahl, MD, FACS  more...
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Several double-masked studies clearly establish the value of systemic aminocaproic acid (ACA, AMICAR) in the prevention of recurrent hemorrhages. [6, 40] If secondary hemorrhages are the result of lysis and retraction of a clot that has produced an occlusion of the traumatized vessel, then prevention of normally occurring clot lysis for 5-6 days should be advantageous to allow the injured blood vessel to more completely repair its integrity. [6] The antifibrinolytic activity of ACA given systemically has been demonstrated in other areas of the body to decrease the incidence of secondary hemorrhage.

ACA retards clot lysis by preventing plasmin from binding to the lysine in the fibrin clot. As a lysine analog, ACA competitively inactivates plasmin by occupying the site on plasmin that would normally bind to fibrin. In a similar manner, ACA binds to plasminogen, so that when activated to plasmin, it cannot attach to fibrin.

When ACA was administered orally in a dosage of 100 mg/kg every 4 hours for 5 days, a statistically significant reduction in the incidence of rebleeding of traumatic hyphemas was observed. [6] Systemic ACA should be used in hyphemas occupying 75% or less of the anterior chamber because the clot may persist in the anterior chamber for an increased period during administration of the drug. The continued retention of the clot in the anterior chamber could be a potential disadvantage with larger Grade 4 hyphemas.

In a prospective study by the authors, as well as 2 additional studies, patient groups treated with ACA and placebo were randomized and double-masked. [6, 23, 41, 40] In the ACA-treated group, the incidence of secondary hemorrhage was 3-4%. [6, 23, 41, 40] In the placebo-treated group, the incidence was 28-33%. ACA in a dosage of 50 mg/kg every 4 hours is equally as effective as 100 mg/kg every 4 hours, orally, for 5 days. [23] The total dosage of ACA should not exceed 30 grams per day.

Systemic ACA should not be used in patients who are pregnant or those with renal or hepatic insufficiency.

Since systemic ACA significantly reduces the incidence of secondary hemorrhage, a topical preparation could decrease the incidence of adverse effects. By concentrating the drug in the aqueous humor, a topical preparation would decrease the systemic concentration of ACA associated with many of the adverse effects.

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