Thrombolytics are medications used to dissolve blood clots that have already formed in the body, such as those causing heart attacks or strokes. This is one of the newest classes of “wonder drug”, since they have made the treatment of a heart attack or stroke in progress possible – it is possible to stop the damage now, rather than ride it out and try to rehabilitate later. These drugs only work on clots that are less than a week old. After that time, the clot changes and no longer responds to thrombolytics (obviously, the faster the treatment is started, the better the result will be).

There is only a short window of opportunity in which thrombolytic administration improves the patient's outcome. Thrombolytic therapy is generally initiated within 4-6 hours of the onset of symptoms, depending on what the site is and the hospital protocol. After a certain period, the damage caused by ischemia (lack of blood flow) is irreversible, and restoring blood flow will not help anymore.

With a stroke, it is critical to determine whether it is a thrombotic (i.e. caused by a clot) or a hemorrhagic (i.e. caused by bleeding) stroke. This is usually done by CAT scan or MRI, which will show any bleeding that may be present. If thrombolytics are administered to a patient experiencing a hemorrhagic stroke, this will totally shut down their ability to clot and thus lead to ever greater bleeding.

Thrombolytics

Brand/Generic Drug Names

Activase/alteplase, Eminase/anistreptase, Streptase/streptokinase, Abbokinase/urokinase
Common uses
deep vein thrombosis, pulmonary embolism, arterial thrombosis, arterial embolism, arteriovenous cannula occlusion, coronary artery thrombus after myocardial infarction, acute, evolving transmural myocardial infarction
Pharmacology
activate conversion of plasminogen to plasmin; plasmin breaks down clots
Class contraindications
allergy, active bleeding, intraspinal surgery, central nervous system neoplasm, ulcerative colitis/enteritis, severe hypertension, renal and hepatic disease, hypocoagulation, COPD, subacute bacterial endocarditis, rheumatic valvular disease, cerebral embolism/thrombosis/hemorrhage, recent intraarterial diagnostic procedure/surgery (10 days), recent major surgery
Class precautions
arterial emboli from L side of heart, pregnancy
Interactions
varies by drug
Adverse Reactions
gastrointestinal, genitourinary, intracranial, retroperitoneal bleeding, anaphylaxis, decreased hematocrit, urticaria, headache, nausea
Additional Information
Assess vital signs, neurological checks and temperature at least every 4 hrs; temp over 104o F indicates internal bleeding; cardiac rhythm for intracoronary
Assess for neurologic changes indicating intracranial bleeding
Assess for allergic reaction or excessive bleeding
Assess blood studies before and during treatment
Administer within 1 wk of thrombus formation
Administer IV using inline filter
Avoid venous or arterial puncture, injections, rectal temperature
Evaluate therapeutic response: resolution of thrombus/embolism
Date of most recent Update
August 29, 2002
Further information is available in the writeup for the specific name(s) of this medication class

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