Streptokinase

Streptokinase


Streptokinase is an extracellular metallo-enzyme produced by beta-haemolytic streptococcus and is used as an effective and cheap clot-dissolving medication in some cases of myocardial infarction (heart attack) and pulmonary embolism.
It belongs to a group of medications known as fibrinolytics, and works by activating plasminogen through cleavage to produce plasmin.
The half life of streptokinase is approximately 20 minutes (quoted in SPC).

Mechanism of action

Plasmin is produced in the blood to break down the major constituent of blood clots fibrin, therefore dissolving clots once they have fulfilled their purpose in stopping bleeding. Extra production of plasmin caused by streptokinase breaks down unwanted blood clots, for example, in the lungs (pulmonary embolism). Streptokinase forms a complex in the plasma with plasminogen to form an activator complex. This complex then forms plasmin from unbound plasminogen.[1]

Administration

It is given intravenously as soon as possible after the onset of a heart attack (acute phase - myocardial infarction) to dissolve clots in the arteries of the heart wall. This reduces the amount of damage to the heart muscle. Streptokinase is a bacterial product so the body will build up an immunity to it. It is recommended that this medication should not be used again after four days from the first administration, as it may not be as effective and can also cause an allergic reaction. For this reason, it is usually given only for a person's first heart attack. Further thrombotic events could be treated with tPA. Overdose of Streptokinase or tPA can be treated with Aminocaproic acid.