are used in medicine
to dissolve blood clots
in a procedure termed thrombolysis
. They limit the damage caused by the blockage of the blood vessel
Thrombolysis is used in myocardial infarction
(heart attack), ischemic strokes
, deep vein thrombosis
and pulmonary embolism
to clear a blocked artery and avoid permanent damage to the perfused tissue (e.g. myocardium
) and death
. A less frequent use is to clear blocked catheters
that are used in long-term medical therapy.
It should be noted that thrombolytic therapy in hemorrhagic strokes is contraindicated, as its use in that situation would prolong bleeding into the intracranial space and cause further damage.
The thrombolytic drugs include:
These drugs are most effective if administered immediately after it has been determined they are clinically appropriate. The advantage of administration is highest within the first ninety minutes, but may extend up to six hours after the start of symptoms.
The drugs are often given in combination with intravenous heparin, or low molecular weight heparin, which are anticoagulant drugs.
Hemorrhagic stroke is a rare but serious complication of thrombolytic therapy. If a patient has had thrombolysis before, an allergy against the thrombolytic drug may have developed (especially after streptokinase
). If the symptoms are mild, the infusion is stopped and the patient is commenced on an antihistamine
before infusion is recommenced. Anaphylaxis
generally requires immediate cessation of thrombolysis.