How is urokinase different from streptokinase?

Urokinase is human-derived and non-antigenic, so it rarely causes allergic reactions or neutralizing antibodies, whereas streptokinase is a bacterial protein that does.

What is the main danger of urokinase?

Bleeding, including serious and intracranial hemorrhage, is the main risk, so it is avoided in people with active bleeding or high hemorrhage risk.

Can urokinase be used to unblock a catheter?

Yes, low local doses of a fibrinolytic are used clinically to clear thrombus-occluded catheters, but this is done by trained clinical staff.

Can I get urokinase without a prescription?

No. It is a prescription medicine administered by clinicians in a monitored setting and is not suitable for any self-administration.

EMA-approvedaka uPA, Abbokinase

Urokinase — Complete Research Guide (2026)

Last updated 2026-06-30

TL;DR

Urokinase (also known as uPA) is a peptide catalogued under Enzymes. Neutral reference entry; EU status: EU-approved prescription medicine.

What is Urokinase?

Urokinase is a human-derived fibrinolytic enzyme (urokinase-type plasminogen activator) used to dissolve thrombi in conditions such as acute pulmonary embolism, peripheral arterial and venous occlusion, and to restore flow in occluded intravascular catheters.

It is a prescription medicine given by clinicians and is supported by randomized trials including the Urokinase Pulmonary Embolism Trial (UPET) and comparative studies against t-PA and surgery.

It is not a research or wellness peptide.

How does Urokinase work?

Urokinase directly converts plasminogen to plasmin, the enzyme that degrades fibrin and lyses clots.

Like streptokinase it produces a systemic lytic state and is not strongly fibrin-specific.

What does the research say about Urokinase?

In acute pulmonary embolism, urokinase accelerates clot lysis and improves early angiographic and hemodynamic resolution compared with heparin alone. ^[1]
Urokinase produces clot lysis in acute pulmonary embolism comparable to recombinant tissue plasminogen activator. ^[2]
Intra-arterial urokinase is an effective alternative to surgery as initial treatment for acute peripheral arterial occlusion of the legs. ^[3]

Clinical research & studies

The references below are the primary sources cited throughout this guide. Each links directly to PubMed or the regulator. Where evidence is preclinical (animal or in-vitro), that is stated rather than implied.

[1] Urokinase pulmonary embolism trial. Phase 1 results: a cooperative study — Urokinase Pulmonary Embolism Trial Study Group, JAMA 1970. (Randomized controlled trial)
[2] Recombinant tissue-type plasminogen activator versus a novel dosing regimen of urokinase in acute pulmonary embolism: a randomized controlled multicenter trial — Goldhaber SZ et al., Journal of the American College of Cardiology 1992. (Randomized controlled trial)
[3] A comparison of recombinant urokinase with vascular surgery as initial treatment for acute arterial occlusion of the legs. Thrombolysis or Peripheral Arterial Surgery (TOPAS) Investigators — Ouriel K et al., New England Journal of Medicine 1998. (Randomized controlled trial)
[4] Streptokinase and urokinase in the treatment of pulmonary thromboemboli; from a national cooperative study — Bell WR et al., Thrombosis and Haemostasis 1976. (Cooperative clinical study)
[5] Treatment of pulmonary embolism with urokinase. Results of clinical trial (phase 1) — Hyers TM et al., Circulation 1970. (Clinical trial)

Dosing context

This is not medical advice or a usage recommendation. Dosing figures are reported research context only, cited from the published literature.

For context only and not as guidance: urokinase regimens are indication-specific, ranging from high systemic doses for pulmonary embolism to low local doses instilled to clear an occluded venous catheter.

All dosing, route, and duration decisions are made by clinicians in a supervised setting.

Side effects & safety profile

Urokinase's principal danger is bleeding, including serious and intracranial hemorrhage, and it is contraindicated in patients with active bleeding, recent surgery, or other high hemorrhage risk.

Unlike streptokinase it is non-antigenic, so allergic reactions and neutralizing antibodies are much less of a concern, but the bleeding risk still confines it to monitored clinical use.

It must be administered and dosed only by medical professionals.

Stacking & combinations

Urokinase is often used with heparin or other anticoagulants for thrombosis, but any such combination adds to bleeding risk and is a clinician-controlled decision only.

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Frequently asked questions

It is a clot-dissolving enzyme used for pulmonary embolism, peripheral arterial and venous thrombosis, and to restore flow in blocked intravascular catheters.

References

[1] Urokinase pulmonary embolism trial. Phase 1 results: a cooperative study — Urokinase Pulmonary Embolism Trial Study Group, JAMA 1970. PMID: 5536580. View sourceStudy: Randomized controlled trialUrokinase plus heparin sped early clot resolution in acute pulmonary embolism versus heparin alone.
[2] Recombinant tissue-type plasminogen activator versus a novel dosing regimen of urokinase in acute pulmonary embolism: a randomized controlled multicenter trial — Goldhaber SZ et al., Journal of the American College of Cardiology 1992. PMID: 1607532. View sourceStudy: Randomized controlled trialUrokinase and rt-PA achieved broadly comparable thrombolytic efficacy in acute pulmonary embolism.
[3] A comparison of recombinant urokinase with vascular surgery as initial treatment for acute arterial occlusion of the legs. Thrombolysis or Peripheral Arterial Surgery (TOPAS) Investigators — Ouriel K et al., New England Journal of Medicine 1998. PMID: 9545358. View sourceStudy: Randomized controlled trialIntra-arterial recombinant urokinase gave outcomes comparable to surgery with fewer open procedures.
[4] Streptokinase and urokinase in the treatment of pulmonary thromboemboli; from a national cooperative study — Bell WR et al., Thrombosis and Haemostasis 1976. PMID: 785689. View sourceStudy: Cooperative clinical studyBoth fibrinolytics resolved pulmonary thromboemboli, informing comparative use and bleeding-risk understanding.
[5] Treatment of pulmonary embolism with urokinase. Results of clinical trial (phase 1) — Hyers TM et al., Circulation 1970. PMID: 5492546. View sourceStudy: Clinical trialUrokinase improved lysis of pulmonary emboli in early clinical evaluation.

This article is for educational and research purposes only. Peptides discussed here are not approved for human consumption by the FDA, EMA, or equivalent regulators outside of specific clinical contexts. Always consult a licensed medical professional before any therapeutic use.