AMINOCAPROIC ACID

By | 2010-06-14

Chemistry

An inhibitor of fibrinolysis, aminocaproic acid is a synthetic monamino carboxylic acid occurring as a fine, white crystalline powder. It is slightly soluble in alcohol and freely soluble in water and has pKa’s of 4.43 and 10.75. The injectable product has its pH adjusted to approximately 6.8. Aminocaproic acid may also be known by the acronym EACA.

Storage – Stability – Compatibility

Products should be stored at room temperature. Avoid freezing liquid preparations. Discoloration will occur if aldehydes or aldehydic sugars are present. When given as an intravenous infusion, normal saline, D5W and Ringer’s Injection have been recommended to be used as the infusion diluent.

Pharmacology

Aminocaproic acid inhibits fibrinolysis via its inhibitory effects on plasminogen activator substances and also via some antiplasmin action.

Aminocaproic acid is thought to affect degenerative myelopathy by its antiprotease activity, thereby reducing the activation of inflammatory enzymes that damage myelin.

Uses – Indications

Aminocaproic acid has been used as a treatment to degenerative myelopathy (seen primarily in German shepherds). In humans, it is primarily used for treating hyperfibrinoly-sis-induced hemorrhage.

Pharmacokinetics

In humans, the drug is rapidly and completely absorbed after oral administration. The drug is well distributed in both intravascular and extravascular compartments and penetrates cells (including red blood cells). It unknown if the drug enters maternal milk. It does not bind to plasma proteins. Terminal half life is about 2 hours in humans and the drug is primarily renally excreted as unchanged drug.

Contraindications – Precautions – Reproductive Safety

Aminocaproic acid is contraindicated in patients with active intravascular clotting. It should be used when the benefits outweigh the risks in patients with preexisting cardiac, renal or hepatic disease. Some, but not all, animal studies have demonstrated teratogenicity; use when risk to benefit ratio merits.

Adverse Effects – Warnings

In dogs treated, about 1% exhibit symptoms of GI irritation.

Overdosage

Acute Toxicity

There is very limited information on overdoses with aminocaproic acid. The IV lethal dose in dogs is reportedly 2.3 g/kg. At lower IV overdosages, tonic-clonic seizures were noted in some dogs. There is no known antidote, but the drug is dialyzable.

Drug Interactions

Hypercoagulation states may occur in patients receiving estrogens.

Laboratory Considerations

Serum potassium may be elevated by aminocaproic acid especially in patients with preexisting renal failure.

Doses

Doses for dogs:

For adjunctive treatment of degenerative myelopathy (seen primarily in German shepherds): a) In combination with exercise, vitamin support (vitamin B-complex, vitamin E), and analgesia (if required; using acetaminophen): Aminocaproic acid: 500 mg (regardless of size of animal, approximate dose is 15 mg/kg) PO q8h. Mix 192 ml of the 250 mg/ml injection with 96 ml of hematinic compound (e.g. Lixotinic®) producing a 288 ml final volume. Give 3 ml per dose (500 mg). Store solution in refrigerator. Clinical improvement seen within 8 weeks. (Clemmons 1991)

Client Information

Drug costs to treat a German shepherd-sized dog can be substantial.

Dosage Forms – Preparations – FDA Approval Status – Withholding Times

Veterinary-Approved Products:

None

Human-Approved Products:

Aminocaproic Acid Tablets 500 mg; Aminocaproic Oral Solution 250 mg/ml; Amicar® (Immunex); (Rx)

Aminocaproic Acid Injection for Intravenous Infusion 250 mg/ml (5 gram); Amicar® Intravenous (Immunex); Generic; (Rx)