g. Tranexamic Acid (Cyklokapron) and Aprotinin (Trasylol). Tranexamic
acid is a competitve inhibitor of plasminogen activation. Its action is similar to
aminocaproic acid but approximately 10x more potent. It is used in hemophiliacs
undergoing invasive procedures. Apotinin is a natural protease inhibitor that inhibits
plasmin. It is used prophylactically in patients undergoing coronary artery bypass
surgery to prevent peri-operative blood loss.
NOTE: The administration of blood products (whole blood, fresh frozen plasma, or
cryoprecipitate) may be used in place of any or all of the above agents to correct excess
bleeding. They are often the fastest means of correcting excess anticoagulation.
Although each of the drugs discussed above has side effects, the risk/benefit of a
transfusion must be weighed in each patient.
Section III. ANTICOAGULANTS
Just as there are conditions of excess bleeding (anticoagulation), so are there
conditions in which excess clotting (coagulation) may be detrimental to the patient. The
major components that promote excess clot formation are: 1) venous stasis (altered or
decreased blood flow to the deep veins of the lower extremities) which occurs with
impaired mobility (traumatic injury, obesity); 2) vascular injury which occurs as the
result of mechanical or chemical trauma causing an inflammation of the vessel; and 3)
hypercoagulability which results from a deficiency of natural anticoagulants
(antithrombin III, protein C, protein S) or a specific disease state (cancer).
Anticoagulants are essential to correcting the propensity to clot. However, they
are a potentially dangerous class of drugs. One reason for their dangerous status is
that anticoagulants interact with a variety of medications (over the counter and legend).
Second, there is always a risk of uncontrolled bleeding when you inhibit a process that
promotes clotting. One of the most important interactions to remember is the
combination of anticoagulants with other drugs--especially salicylates (aspirin) or non-
steroidal antiinflammatory drugs (ibuprofen, naproxen). These products can potentiate
the effects of the anticoagulants by inhibiting platelet aggregation which is the first line
of defense to stop bleeding.
5-6. IMPORTANT WARNING ASSOCIATED WITH THE ANTICOAGULANTS
There is one warning common to all anticoagulants. When you dispense an
anticoagulant to a patient you should tell the person that they should not take any other
medication--over the counter or legend--without first consulting the physician who
prescribed the anticoagulant. Emphasize that over-the-counter products such as aspirin
and ibuprofen are also classified as medications.