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# Streptokinase

A streptococcal protein that forms a complex with plasminogen to dissolve clots. Cheap but antigenic and not fibrin-selective.

Updated 2026-11-01

- Class: [Thrombolytics (fibrinolytics)](https://durgical.com/en/pharmacology/classes/thrombolytics/)
- Enzyme: Plasminogen (streptokinase–plasminogen activator complex)
- ATC code: B01AD01
- WHO Model List of Essential Medicines

## ⚠ High-alert medication

An error with this medicine can cause serious harm: double checks and protocols are used.

✂**Plasminogen (streptokinase–plasminogen activator complex)**Streptokinase

ⓘ The figure shows the catalytic domain of human plasmin bound to streptokinase, the complex that converts further plasminogen into plasmin.

**Target in 3D:** Plasminogen (streptokinase–plasminogen activator complex). PDB structure 1BML (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/1BML) · Drag to rotate · pinch to zoom

## Mechanism of action

Streptokinase is not an enzyme itself. It binds plasminogen one-to-one and the complex becomes an active plasminogen activator that converts other plasminogen molecules, free or fibrin-bound, into plasmin. Because it is not fibrin-selective it causes a marked systemic lytic state. Being a bacterial protein, it provokes antibodies.

- Streptokinase binds a plasminogen molecule
- The complex activates other plasminogen, free or on fibrin
- Plasmin digests fibrin and fibrinogen

## Pharmacokinetics

**Elimination**
Partly neutralised by pre-existing anti-streptococcal antibodies

## Indications

- Acute ST-elevation myocardial infarction where fibrin-specific agents or angioplasty are not available [Myocardial Infarction (Heart Attack) →](https://durgical.com/en/conditions/myocardial-infarction/)
- Pulmonary embolism with haemodynamic instability [Pulmonary embolism →](https://durgical.com/en/conditions/pulmonary-embolism/)

## Adverse effects

### Common

- Fever and chills
- Allergic reactions
- Bleeding

### Serious (rare, important)

- Intracranial haemorrhage
- Severe allergic reactions
- Loss of effect from neutralising antibodies

## Contraindications

- Previous intracranial haemorrhage, or a known cerebral vascular lesion or brain tumour
- Active bleeding or a bleeding disorder
- Suspected aortic dissection
- Recent ischaemic stroke, significant head trauma or brain or spinal surgery
- Previous streptokinase exposure or allergy to it

## Key interactions

**Heparin, anticoagulants and antiplatelets (aspirin, clopidogrel)**
Add to the bleeding risk; serious haemorrhage is more frequent when heparin is given at the same time

**Warfarin (raised INR)**
Current warfarin use with a raised INR is a relative contraindication

## What is monitored

- Neurological status and blood pressure
- Signs of bleeding; haemoglobin and coagulation tests
- Reperfusion: ECG and symptoms in myocardial infarction
- Signs of allergy during the infusion

## Administration and safety

- Intravenous infusion; have anaphylaxis treatment ready
- Ask about previous treatment with streptokinase before giving it

## Nursing care

- Neurological checks and blood pressure often during and after the infusion; a sudden headache, vomiting or a drop in consciousness suggests intracranial bleeding
- Look for bleeding at puncture sites, gums, urine and stool
- Avoid new arterial punctures, intramuscular injections and unnecessary venepunctures
- Watch for fever, rash, bronchospasm and hypotension during the infusion

## Pregnancy and breastfeeding

Pregnancy is a relative contraindication to thrombolysis; it is used only for a life-threatening clot.

## Memory aid

Strepto = «strange» protein: the body remembers it, so no second time.

## Test yourself

Think of the answer, then tap the question to see it.

## Is streptokinase an enzyme?

No; it becomes active only after binding plasminogen.

## Why is it usually not repeated in the same patient?

Antibodies form, causing allergy and resistance.

## Why is its systemic lytic state greater than that of alteplase?

It activates free plasminogen as well as fibrin-bound plasminogen.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/streptokinase/)

## Related drugs

- [Alteplase](https://durgical.com/en/pharmacology/alteplase/)

## Related conditions

- [Myocardial Infarction (Heart Attack)](https://durgical.com/en/conditions/myocardial-infarction/)
- [Pulmonary embolism](https://durgical.com/en/conditions/pulmonary-embolism/)

[← Back to the class: Thrombolytics (fibrinolytics)](https://durgical.com/en/pharmacology/classes/thrombolytics/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: Farmacología básica y clínica (Katzung), 16.ª ed., cap. 34 (McGraw Hill, 2025); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 36 (McGraw Hill, 2023); [eEML - Electronic Essential Medicines List](https://list.essentialmeds.org/) (World Health Organization, 2025); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=B01AD01) (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/streptokinase/