BMA Concise Guide to Medicine & Drugs


Brand name Streptase

Used in the following combined preparation Varidase


Drug group Thrombolytic drug

Overdose danger rating Medium

Dependence rating Low

Prescription needed Yes

Available as generic Yes


Streptokinase, an enzyme produced by streptococcus bacteria, is used in hospitals to dissolve the fibrin of blood clots, especially those in the arteries of the heart and lungs. It is also used on the clots formed in shunts during kidney dialysis. A fast-acting drug, streptokinase is most effective in dissolving any newly formed clots, and it is often released at the site of the clot via a catheter inserted into an artery. Administered in the early stages of a heart attack to dissolve a clot (thrombosis) in the coronary arteries, it can reduce the amount of damage to heart muscle. Because excessive bleeding is a common side effect, treatment is closely supervised.

Streptokinase is a bacterial protein, and can cause allergic reactions when there has been previous infection or immunization with streptococcus bacteria (because of existing antibodies in the blood). In addition, the administration of streptokinase results in production of more antibodies, and this severely reduces the effectiveness of subsequent doses of the drug.


The drug is only given under medical supervision and is not for self administration.

How taken/used Injection.

Frequency and timing of doses By a single injection or continuously over a period of 12–72 hours.

Dosage range Dosage is determined individually by the patient’s condition and response.

Onset of effect As soon as streptokinase reaches the blood clot, it begins to dissolve within minutes. Most of the clot will be dissolved within a few hours.

Duration of action Effect disappears within a few minutes of stopping the drug.

Diet advice None.

Storage Not applicable. This drug is not normally kept in the home.

Missed dose Not applicable. This drug is given only in hospital under close medical supervision.

Stopping the drug The drug is usually given for up to 5 days.

Exceeding the dose Overdose is unlikely since treatment is carefully monitored.


Streptokinase is given only under medical supervision and all of its adverse effects are closely monitored so that they can be dealt with quickly. All of the adverse effects listed here should be reported to medical staff immediately. Excessive bleeding, nausea, and vomiting are the most common side effects. More rarely, fever, wheezing, or abnormal heart rhythms may occur. If a rash, itching, or collapse occur, the drug should be stopped.


Anticoagulant drugs There is an increased risk of bleeding when these are taken at the same time as streptokinase.

Antiplatelet drugs There is an increased risk of bleeding if these drugs are given with streptokinase.


Streptokinase is only prescribed under close medical supervision, usually only in life-threatening circumstances.

Pregnancy Not usually prescribed. If used during the first 18 weeks of pregnancy there is a risk that the placenta may separate from the wall of the uterus.

Breast-feeding It is not known whether the drug passes into breast milk or is harmful. Discard breast milk for first 24 hours after treatment.

Infants and children Not recommended.

Over 60 Increased likelihood of bleeding into the brain.

Driving and hazardous work Not applicable.

Alcohol Not applicable.


Streptokinase is never used long-term.

Further doses Because administration of streptokinase causes the body to produce antibodies against the drug, any subsequent doses have a significantly reduced therapeutic effect. Therefore if subsequent treatment with thrombolytic (“clot busting”) drugs is required, a different drug is given, such as alteplase.