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Thrombolytic — Catheter-Directed Thrombolysis / Catheter Occlusion Pregnancy: Contraindicated — risk of maternal haemorrhage; use only for immediately life/limb-threatening thrombosis

Urokinase

Brand names: Syner-KINASE, Medakinase

Adult dose

Dose: Catheter-directed thrombolysis (peripheral arterial/DVT): 4400 units/kg IV loading then 4400 units/kg/hour; Occluded catheter/PICC: 5000 units in 1–2 mL instilled into catheter lumen
Route: Intravenous infusion (CDT) or intracatheter instillation
Frequency: Continuous infusion (CDT); single instillation (catheter lock)
Max: CDT: individually guided by imaging and fibrinogen monitoring; catheter lock: 5000–25,000 units
Non-antigenic (human-derived) — unlike streptokinase; can be re-used without risk of allergic reaction. Directly converts plasminogen to plasmin. Used in catheter-directed thrombolysis where alteplase unavailable or as alternative. Monitor fibrinogen — stop if <1 g/L. Used for clearing occluded vascular access catheters in oncology/renal patients.

Paediatric dose

Dose: 4400 units/kg loading then 4400 units/kg/hour units/kg
Route: IV or intracatheter
Frequency: Continuous or single instillation
Max: Under specialist guidance
BNFc: used in paediatric catheter occlusion and peripheral vascular thrombosis under specialist haematology/radiology guidance

Dose adjustments

Renal

No dose adjustment required — not renally cleared as active drug

Hepatic

Use with caution in severe hepatic impairment — impaired clotting synthesis

Paediatric weight-based calculator

BNFc: used in paediatric catheter occlusion and peripheral vascular thrombosis under specialist haematology/radiology guidance

Clinical pearls

  • Non-antigenic advantage over streptokinase — urokinase is human-derived (originally from urine/renal cells, now recombinant); no antibody formation, no re-use restrictions
  • Direct plasminogen activator: urokinase directly cleaves plasminogen → plasmin; no intermediate complex formation unlike streptokinase
  • Catheter clearance: widely used in oncology/renal units to restore patency of Hickman lines, PICCs, dialysis catheters — instilled and left to dwell for 1–4 hours then aspirated
  • CDT protocols vary by institution — alteplase is more commonly used in UK for peripheral arterial CDT; urokinase more common in some catheter clearance protocols
  • Fibrinogen monitoring every 4 hours during systemic infusion — stop if <1 g/L to prevent catastrophic fibrinolysis

Contraindications

  • Active internal bleeding
  • Recent surgery/trauma (<10 days)
  • Recent stroke (<3 months)
  • Uncontrolled hypertension
  • Coagulopathy
  • Intracranial neoplasm

Side effects

  • Bleeding (major and minor)
  • Fever
  • Nausea
  • Reperfusion arrhythmias (if used for coronary)
  • Intracranial haemorrhage (rare with catheter-directed use)
  • Distal embolisation

Interactions

  • Anticoagulants — additive bleeding (often co-administered at low dose during CDT)
  • Antifibrinolytics — antagonise thrombolytic effect
  • Antiplatelets — additive bleeding

Monitoring

  • Fibrinogen (4-hourly during infusion)
  • aPTT (co-administered heparin)
  • FBC and coagulation screen
  • Imaging for thrombus resolution
  • Catheter site and access point for haemostasis

Reference: BNFc; BNF 90; MHRA SPC Syner-KINASE; ESC/ESVS Peripheral Arterial Disease Guidelines; British Society for Haematology Catheter Thrombosis Guidelines. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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