Thrombolytic drugs 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.
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Thrombolysis is used in myocardial infarction (heart attack), thromboembolic strokes, deep vein thrombosis and pulmonary embolism to clear a blocked artery and avoid permanent damage to the perfused tissue (e.g. myocardium, brain, leg) and death. A less frequent use is to clear blocked catheters that are used in long-term medical therapy.
Thrombolytic therapy in hemorrhagic strokes is contraindicated, as its use in that situation would prolong bleeding into the intracranial space and cause further damage.
| Condition | Prothrombin time | Partial thromboplastin time | Bleeding time | Platelet count |
|---|---|---|---|---|
| Vitamin K deficiency or warfarin | prolonged | normal or mildly prolonged | unaffected | unaffected |
| Disseminated intravascular coagulation | prolonged | prolonged | prolonged | decreased |
| von Willebrand disease | unaffected | prolonged | prolonged | unaffected |
| Hemophilia | unaffected | prolonged | unaffected | unaffected |
| Aspirin | unaffected | unaffected | prolonged | unaffected |
| Thrombocytopenia | unaffected | unaffected | prolonged | decreased |
| Liver failure, early | prolonged | unaffected | unaffected | unaffected |
| Liver failure, end-stage | prolonged | prolonged | prolonged | decreased |
| Uremia | unaffected | unaffected | prolonged | unaffected |
| Congenital afibrinogenemia | prolonged | prolonged | prolonged | unaffected |
| Factor V deficiency | prolonged | prolonged | unaffected | unaffected |
| Factor X deficiency as seen in amyloid purpura | prolonged | prolonged | unaffected | unaffected |
| Glanzmann's thrombasthenia | unaffected | unaffected | prolonged | unaffected |
| Bernard-Soulier syndrome | unaffected | unaffected | prolonged | decreased or unaffected |
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 sixty 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.
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