2.10 Fibrinolytic drugs
Streptokinase (IV injection) is recommended for immediate use after acute myocardial infarction, together with aspirin, in patients with no contra-indications to its use. It may also be of value in the treatment of life-threatening pulmonary embolism. Its role in deep-vein thrombosis remains unclear. It may also be used to unblock thrombosed arteriovenous shunts and in some patients with peripheral arterial thrombosis/embolism.
Strepokinase is contra-indicated in patients who have experienced previous allergic reactions or have been treated with the drug more than 4 days previously.
Tenecteplase (IV injection) is an alternative to streptokinase in acute myocardial infarction and is used in the following:
- patients who have received streptokinase more than 4 days previously
- patients who have developed a hypersensitivity reaction to streptokinase
- patients with low blood pressure
- patients < 75 years with anterior myocardial infarction up to 4 hours after onset of symptoms, where tenecteplase may be more efficacious than streptokinase.
Tenecteplase is given by IV bolus injection for acute myocardial infarction. A bolus IV injection of heparin is also given immediately before or after tenecteplase followed by continuous IV infusion of heparin. (ASSENT 2 Lancet 1999, 354, 716-722, ASSENT 3 Lancet 2001, 358, 605-613, See Data Sheet). The dosage of tenecteplase and heparin are adjusted to patient's body weight. Tenecteplase is also available for use in acute myocardial infarction by GPs.
PRESCRIBING POINTS FOR FIBRINOLYTIC DRUGS
- In acute myocardial infarction, streptokinase and tenecteplase reduce mortality. Fibrinolytic treatment should be initiated as soon as possible. The potential benefit lessens as the delay from the onset of major symptoms increases, but the value of treatment within the first 12 hours is reasonably well established.
- Adjuvant therapy with heparin is required with tenecteplase to prevent re-thrombosis.