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Thrombolytic — Catheter-Directed Thrombolysis / Catheter Occlusion

Urokinase

Brand names: Syner-KINASE, Medakinase

Urokinase is a thrombolytic (fibrinolytic) enzyme used to dissolve thrombi, including in the management of certain thromboembolic occlusions and blocked vascular access devices.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: THROMBOSED INTRAVASCULAR CATHETERS AND CANNULAE (adult, catheter-lock instillation) — UK SPC §4.2 verbatim: '5,000 to 25,000 IU Syner-KINASE should be dissolved in the volume of solvent required to completely fill the lumen of the catheter or cannula and locked for a duration of 20 to 60 minutes. The lysate is then aspirated and the procedure repeated if necessary. Alternatively, an infusion of up to 250,000 IU Syner-KINASE can be administered into the catheter or cannula over a period of 90 to 180 minutes using a solution of 1,000 to 2,500 IU/ml in the solvent.' || EXTENSIVE ACUTE PROXIMAL DEEP VEIN THROMBOSIS (adult, systemic intravenous infusion) — §4.2 verbatim: 'An initial loading dose of 4,400 IU/kg body weight dissolved in 15 ml solvent should be infused in a peripheral vein over 10 minutes followed by 4,400 IU/kg/hour for 12-24 hours.'
Route: Catheter-occlusion regimen: local instillation into the lumen of the occluded catheter or cannula (lock), or infusion into the catheter/cannula. DVT regimen: intravenous infusion into a peripheral vein. §4.2 verbatim: 'The route of administration is by intravenous infusion, intra-arterial injection or local instillation. It must not be given as a subcutaneous or intramuscular injection.' 'Syner-KINASE must be restricted to hospital use only. Adequate diagnostic and monitoring techniques should be available.'
Frequency: Catheter lock: single 20–60 minute dwell, then aspirate; 'the procedure repeated if necessary'. Alternative intracatheter infusion: over 90 to 180 minutes. DVT: 10-minute loading infusion followed by a continuous infusion for 12–24 hours.
Max: For the CATHETER-OCCLUSION indication: maximum 25,000 IU per lock instillation (SPC range '5,000 to 25,000 IU'), and for the alternative intracatheter infusion the SPC caps the dose explicitly — 'an infusion of up to 250,000 IU Syner-KINASE can be administered into the catheter or cannula over a period of 90 to 180 minutes'. For the DVT regimen NO maximum dose is stated: 4,400 IU/kg/hour is a RATE, not a ceiling, and the only stated bound is the 12–24 hour duration. Do not transfer either catheter figure to the systemic regimens.
Source: UK SPC (eMC) for Syner-KINASE 10,000 IU powder for solution for injection/infusion, §4.2. 'The dose of Syner-KINASE may be adjusted individually depending on the clinical condition and response to treatment.' OTHER SPC INDICATIONS, quoted verbatim and clearly scoped (each has its own regimen — do not mix them with the two doses above): (1) ACUTE MASSIVE PULMONARY EMBOLISM — 'An initial loading dose of 4,400 IU/kg body weight dissolved in 15 ml solvent should be infused in a peripheral vein over 10 minutes followed by 4,400 IU/kg/hour for 12 hours. Alternatively, a bolus injection into the pulmonary artery repeated for up to 2 times at 24-hour intervals may be used. An initial dosage of 15,000 IU/kg body weight may be adjusted if necessary for subsequent injections depending on the plasma fibrinogen concentration produced by the previous injection.' (2) ACUTE OCCLUSIVE PERIPHERAL ARTERIAL DISEASE WITH LIMB THREATENING ISCHAEMIA (catheter-directed intra-arterial) — 'A solution of 2,000 IU/ml (500,000 IU Syner-KINASE dissolved in 250 ml solvent) should be infused into the clot with angiographic monitoring of progress of treatment. It is recommended that the rate of infusion should be 4,000 IU/minute for 2 hours when angiography should be repeated. Following this, the catheter should be advanced into the occluded segment of vessel and Syner-KINASE infused at the same rate of 4,000 IU/minute for another 2 hours. The process can be repeated up to 4 times if flow has not been achieved. Once a channel has been created through the blocked segment, the catheter may be withdrawn until it lies proximal to the remaining thrombus. Infusion should continue at the rate of 1,000 IU/minute until the clot has completely lysed. Usually, a dose of 500,000 IU over 8 hours should be sufficient. If the length of the clot has not been reduced by more than 25% after the initial dose of 500,000 IU and further reductions of 10% by subsequent infusions of 500,000 IU, discontinuation of treatment should be considered.' ELDERLY: 'The initial dosage should be the same as in adults but it may be adjusted subsequently depending on response. Syner-KINASE should be used with caution in elderly patients.' HUMAN-SOURCED PRODUCT (§4.4): 'Syner-KINASE contains highly purified urokinase which is obtained from human urine. Products manufactured from human source materials have the potential to transmit infectious agents. Procedures to control such risks strongly reduce but cannot completely eliminate the risk of transmitting infectious agents.' NOT VERIFIED BY THIS SOURCE: the live page's '5000 units in 1–2 mL' catheter volume (the SPC specifies the volume required to fill the lumen, not a fixed 1–2 mL), and its 'stop if fibrinogen <1 g/L' rule (the SPC's stated threshold is 'the fibrinogen level should not fall below 100 mg/dl', and it is stated for renal/hepatic impairment). §4.4 was truncated at the source-fetch limit — 'Therapeutic monitoring: Before thrombolytic therapy…' was cut off, so the monitoring set below is incomplete.

Paediatric dose

Route: Local instillation into the lumen of a thrombosed central venous catheter (catheter lock) only
Frequency: Locked for 20 to 60 minutes, then aspirated; repeated if necessary — 'using the same lock procedure as in adults'
Max: 25,000 IU per lock instillation, i.e. the top of the adult lock range that the SPC applies unchanged to children
Presentation: Dissolved in the volume of solvent required to completely fill the lumen of the catheter or cannula (the SPC specifies a lumen-fill volume, not a fixed concentration, for the lock; the alternative intracatheter infusion uses 1,000 to 2,500 IU/ml) NO PER-KG PAEDIATRIC DOSE — dosePerKg deliberately left null because the only paediatric use the SPC permits is the catheter lock, which is a lumen-fill dose, not a weight-based one. UK SPC §4.2 verbatim: 'There is very limited experience with urokinase in children with thromboembolic occlusive vascular disease and urokinase should not be used in this indication. Syner-KINASE may be used in children of all ages for the treatment of thrombosed central venous catheters using the same lock procedure as in adults.' SAFETY CORRECTION: the live page's paediatric entry ('4400 units/kg loading then 4400 units/kg/hour', route 'IV or intracatheter') contradicts this SPC — the 4,400 IU/kg systemic regimen belongs to adult DVT/PE and the SPC states urokinase SHOULD NOT be used in children for thromboembolic occlusive vascular disease. It must not be carried forward. The adult lock dose that the SPC extends to children of all ages is '5,000 to 25,000 IU... dissolved in the volume of solvent required to completely fill the lumen of the catheter or cannula and locked for a duration of 20 to 60 minutes. The lysate is then aspirated and the procedure repeated if necessary.' Verify any under-18 use against a children's formulary and with the specialist haematology/interventional radiology team.

Dose adjustments

Renal

UK SPC §4.2 verbatim: 'A dose reduction may be required in patients with impaired renal or hepatic impairment (see section 5.2). In these cases, the fibrinogen level should not fall below 100 mg/dl.' No numeric reduction is specified. §4.3 makes 'Severe hepatic or renal insufficiency unless the patient is receiving renal replacement therapy' an absolute contraindication, and §4.4 lists 'Moderate coagulation defects including those due to severe renal or hepatic disease' among conditions in which bleeding risk is increased.

Hepatic

Same SPC sentence as for renal impairment: 'A dose reduction may be required in patients with impaired renal or hepatic impairment (see section 5.2). In these cases, the fibrinogen level should not fall below 100 mg/dl.' Severe hepatic insufficiency is an absolute contraindication (§4.3), and severe hepatic disease causing moderate coagulation defects increases bleeding risk (§4.4).

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • Hypersensitivity to the active substance or to any of the excipients listed in section 6.1
  • Active clinically relevant bleeding
  • Recent severe gastrointestinal bleeding
  • Recent major surgery
  • Recent cerebrovascular accident (e.g. within 2 months)
  • Recent trauma including cardiopulmonary resuscitation, thoracic or neurosurgery (e.g. within 2 months)
  • Severe hypertension
  • Severe hepatic or renal insufficiency unless the patient is receiving renal replacement therapy
  • Blood coagulation defects and severe thrombocytopenia
  • Aneurysm and arteriovenous malformation
  • Intracranial neoplasm or other neoplasm with risk of haemorrhage
  • Acute pancreatitis or pericarditis or bacterial endocarditis or sepsis
  • Recent obstetric delivery

Side effects

  • Haemorrhage is the most frequent and severe effect — 'Severe spontaneous bleeding, including fatalities resulting from cerebral haemorrhage, has occurred during urokinase therapy. Less severe spontaneous bleeding has occurred approximately twice as frequently as that occurring during heparin therapy. Patients with pre-existing haemostatic defects have the greatest risk of spontaneous bleeding.'
  • Very common: haemorrhage including from puncture site and wound, epistaxis, gingival bleeding; thromboembolism; embolism including pulmonary embolism; microscopic haematuria; decrease in haematocrit without clinically detectable haemorrhage ('reported in approximately 20% of patients receiving urokinase'); transient increase in transaminases
  • Common: stroke; gastrointestinal, intracranial, retroperitoneal, urogenital and muscle haemorrhage; artery dissection; cholesterol embolism; fever, chills
  • Uncommon: intrahepatic haemorrhage; renal failure
  • Rare: hypersensitivity reactions including urticaria, dyspnoea, hypotension, flushing, rash; vascular pseudoaneurysm; macroscopic haematuria. Very rare: anaphylaxis — 'Urokinase is reportedly non-antigenic but mild hypersensitivity reactions including urticaria, rash, bronchospasm and very rare cases of fatal anaphylaxis have been reported.'
  • Infusion reactions — 'fever and shaking chills (rigors)... Other infusion reactions include dyspnoea, cyanosis, hypoxemia, acidosis, back pain, and nausea and/or vomiting; these reactions generally occurred within one hour of beginning urokinase infusion.' Symptomatic treatment is usually sufficient for urokinase-induced fever, 'however, acetylsalicylic acid should not be used.'
  • Embolism — 'Embolic episodes may occur after fragments of clot have been released. Cholesterol embolisms have also been reported.'

Interactions

  • Other thrombolytics, anticoagulants or anti-platelet agents — 'Concomitant administration of urokinase with other thrombolytics, anticoagulants or anti-platelet agents may increase the risk of bleeding' (§4.4)
  • Angiotensin converting enzyme (ACE) inhibitors — 'Concomitant administration of urokinase with angiotensin converting enzyme (ACE) inhibitors, may increase the risk of angioedema' (§4.4)
  • Acetylsalicylic acid should not be used to treat urokinase-induced fever (§4.8)
  • NOTE: §4.5 was not retrieved in this bundle — this interaction list is incomplete

Monitoring

  • SETTING (§4.2): 'Syner-KINASE must be restricted to hospital use only.
  • Adequate diagnostic and monitoring techniques should be available.' FIBRINOGEN: in renal or hepatic impairment 'the fibrinogen level should not fall below 100 mg/dl' (§4.2)
  • for repeated pulmonary-artery bolus injections the dose 'may be adjusted if necessary for subsequent injections depending on the plasma fibrinogen concentration produced by the previous injection'.
  • ANGIOGRAPHY guides the peripheral arterial regimen — infuse 'with angiographic monitoring of progress of treatment', repeating angiography after the first 2 hours, and consider discontinuation if the clot length has not reduced by more than 25% after the initial 500,000 IU and by a further 10% with subsequent 500,000 IU infusions (§4.2).
  • BLEEDING PRECAUTIONS (§4.4): 'Intramuscular injections and unnecessary handling of the patient should be avoided.
  • Venipuctures and invasive venous procedures should be performed as infrequently as possible and with care to minimise bleeding...
  • Arterial invasive procedures must be avoided before and during urokinase treatment...
  • If an arterial puncture is absolutely essential, it should be performed by a physician experienced in the procedure, using a radial or brachial rather than a femoral artery.
  • Direct pressure should be applied at the puncture site for at least 30 minutes, a pressure dressing applied, and the site checked frequently for evidence of bleeding.' 'If severe bleeding occurs during systemic treatment with Syner-KINASE, treatment should be stopped immediately and measures to manage the bleeding implemented.' HIGHER-RISK GROUPS to review closely (§4.4): recent surgery
  • severe cerebrovascular disease
  • moderate coagulation defects including those due to severe renal or hepatic disease
  • high likelihood of a left heart thrombus
  • cavernous pulmonary diseases
  • genitourinary tract disease with existing or potential bleeding sources (e.g. implanted bladder catheter)
  • known septic thrombotic disease
  • elderly patients, especially those over 75 years.
  • NOTE: the §4.4 'Therapeutic monitoring' paragraph was truncated at the source-fetch limit — this list is incomplete.

Clinical monograph

How it works

It directly converts plasminogen to plasmin, which degrades fibrin within the thrombus and so promotes clot lysis.

Prescribing in practice

  • Bleeding is the principal hazard; it is contraindicated where there is active internal bleeding, recent surgery or trauma, or a high risk of intracranial haemorrhage.
  • Concurrent anticoagulants or antiplatelet agents substantially increase the risk of serious haemorrhage.
  • Use should be confined to settings with facilities to manage bleeding complications and to monitor the patient closely.

Monitoring

Monitor for signs of bleeding and haemodynamic instability throughout treatment, with relevant coagulation parameters as indicated by the clinical situation.

Counselling the patient

  • Tell the team at once about any unusual bleeding, bruising, or blood in the urine or stool.
  • Avoid unnecessary injections and procedures during treatment to reduce bleeding risk.
  • Treatment is given and supervised in a closely monitored clinical setting.

Evidence & guidelines

Use of fibrinolytic agents such as urokinase is guided by established thrombolysis principles and the relevant product information.

Reference: MHRA SPC Syner-KINASE; ESC/ESVS Peripheral Arterial Disease Guidelines; British Society for Haematology Catheter Thrombosis Guidelines; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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