Amicar (aminocaproic acid) is a medication used to control excessive bleeding caused by the body’s clot-dissolving system being too active. It works by slowing down fibrinolysis, the natural process your body uses to break down blood clots, so that clots stay in place long enough to stop bleeding. It’s available in oral tablets, liquid form, and as an intravenous solution given in hospitals.
How Amicar Works
When you’re injured or have surgery, your body forms blood clots to seal off damaged blood vessels. Normally, once healing begins, your body gradually dissolves those clots through a process called fibrinolysis. Sometimes this clot-dissolving process kicks in too aggressively or too early, causing bleeding that won’t stop on its own.
Amicar steps in by blocking the enzymes that activate your body’s clot-dissolving machinery. Specifically, it interferes with the substances that convert an inactive protein in your blood (plasminogen) into its active clot-dissolving form. To a lesser extent, it also directly dampens clot-dissolving activity that’s already underway. The drug is cleared primarily through the kidneys, with a short half-life of about two hours, meaning it moves through your system relatively quickly.
Primary Uses
Amicar is FDA-approved to enhance clot formation when excessive fibrinolysis contributes to bleeding. The most common clinical scenarios include:
- Heart surgery: Bleeding is a frequent complication during and after cardiac procedures, especially those involving cardiopulmonary bypass. Giving Amicar before or during surgery can reduce blood loss and lower the chances of needing a blood transfusion.
- Urinary tract bleeding: Your urinary system naturally has high clot-dissolving activity. After prostate surgery, kidney surgery, or in people with kidney or bladder diseases, this can lead to dangerous bleeding. Amicar helps stabilize clots in the urinary tract.
- Blood disorders: People with conditions like aplastic anemia, where the bone marrow doesn’t produce enough blood cells, may experience bleeding that Amicar can help control.
- Liver disease: The liver produces many clotting factors, so conditions like cirrhosis can tip the balance toward excessive clot breakdown.
- Certain cancers: Tumors of the prostate, lungs, stomach, and cervix can trigger abnormal fibrinolysis and bleeding.
Amicar is also used following severe trauma, oxygen deprivation, and shock, all of which can trigger life-threatening bleeding through overactive clot dissolution in the urinary system and elsewhere.
Use in Dental Procedures and Bleeding Disorders
One of the more common situations where patients encounter Amicar outside of a hospital is dental work. People with hemophilia or other bleeding disorders face a real risk of prolonged bleeding after tooth extractions or oral surgery. The World Federation of Hemophilia recommends antifibrinolytic agents like Amicar as an add-on treatment alongside clotting factor replacement therapy, both before and after dental procedures. This combination reduces the amount of clotting factor needed and helps keep bleeding under control during recovery.
Amicar can be taken by mouth or even swished in the mouth as a rinse to act directly on the surgical site. For people with bleeding disorders who develop resistance to standard clotting treatments, Amicar serves as an alternative way to promote clotting.
How It Compares to Tranexamic Acid
Tranexamic acid (TXA) is a closely related drug that works through the same mechanism. In lab terms, TXA is roughly 10 times more potent than Amicar, which means lower doses are needed to achieve a similar effect. Despite this difference in potency, head-to-head comparisons in cardiac surgery tell a more nuanced story.
A meta-analysis published in Circulation found no significant difference between the two drugs in total blood loss, transfusion rates, or the need for repeat surgery to control bleeding. There was also no meaningful difference in serious complications like stroke, heart attack, or death. In practice, this means both drugs perform similarly in the operating room, and the choice between them often comes down to hospital preference, cost, and availability. TXA has become more widely used in orthopedic procedures like hip and knee replacements, while Amicar remains a staple in cardiac surgery settings.
Important Safety Concerns
Because Amicar works by keeping clots intact, it carries an inherent risk of unwanted clotting. It should not be used when there is active abnormal clotting happening inside your blood vessels. This distinction is critical in a condition called disseminated intravascular coagulation (DIC), where the body forms tiny clots throughout the bloodstream while simultaneously bleeding. Using Amicar in DIC without additional treatment to manage the clotting can make the situation far worse.
Before prescribing Amicar, doctors need to determine whether bleeding is caused by excessive clot dissolution (where the drug helps) or by DIC (where it can be dangerous). This is not always straightforward, and lab tests are typically needed to tell the two apart.
Side Effects
Most people tolerate Amicar well, but it can cause nausea, diarrhea, dizziness, and headaches. A more serious but less common concern is muscle damage. Some patients develop muscle weakness or pain, particularly with prolonged use. This muscle toxicity tends to resolve after stopping the medication, but it’s something to be aware of if you’re taking Amicar for more than a few days.
The most significant risk is blood clot formation in places you don’t want it, such as the legs or lungs. People with a history of blood clots or conditions that predispose them to clotting need careful evaluation before using this drug. Kidney function also matters, since the drug is eliminated almost entirely through the kidneys. Impaired kidney function can cause the drug to build up to higher-than-intended levels.
Amicar has not been formally studied in children for safety and effectiveness, though it is sometimes used off-label in pediatric settings under close medical supervision.