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Fibrin-Specific Thrombolytic (Third-Generation tPA)

Tenecteplase (TNK-tPA — STEMI/Massive PE)

Brand names: Metalyse

Tenecteplase (TNK-tPA) is a single-bolus intravenous fibrinolytic used for thrombolysis in ST-elevation myocardial infarction, and is also used off-label in selected massive pulmonary embolism with haemodynamic compromise.

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: Acute myocardial infarction (STEMI) — single weight-banded intravenous bolus: body weight <60 kg = 6,000 units (30 mg); ≥60 to <70 kg = 7,000 units (35 mg); ≥70 to <80 kg = 8,000 units (40 mg); ≥80 to <90 kg = 9,000 units (45 mg); ≥90 kg = 10,000 units (50 mg).
Route: Intravenous bolus over approximately 10 seconds (UK SPC §4.2; the US TNKase label specifies a single bolus over 5 seconds). Licensed indication for this dose: acute myocardial infarction / STEMI only.
Frequency: Single dose only — one bolus per treatment episode. SPC: 'Treatment with Metalyse should be initiated as early as possible after onset of symptoms.'
Max: Maximum 10,000 units (50 mg tenecteplase). SPC §4.2 verbatim: 'Metalyse should be administered on the basis of body weight, with a maximum dose of 10 000 units (50 mg tenecteplase).'
SCOPE — this dose is the SPC's acute-myocardial-infarction (STEMI) regimen only. The bundle contains NO dose for pulmonary embolism: the SPC states 'The 40 mg and 50 mg presentations are only intended for use in acute myocardial infarction', and neither the UK SPC nor the US TNKase label sections fetched give a PE regimen. Do not read the STEMI bolus above as a PE dose. VOLUME (from the SPC's own table, reconstituted solution): 6 mL / 7 mL / 8 mL / 9 mL / 10 mL for the five weight bands respectively; the US label reconstitutes the 50 mg vial with 10 mL Sterile Water for Injection 'to obtain a final concentration of 5 mg/mL'. ADMINISTRATION: 'The reconstituted solution should be administered intravenously and is for immediate use.' US label: 'Precipitation may occur when TNKase is administered in an intravenous line containing dextrose. Flush dextrose-containing lines with a saline-containing solution prior to and following single bolus administration.' ELDERLY: 'Metalyse should be administered with caution in the elderly (≥ 75 years) due to a higher bleeding risk.' PCI: 'If primary percutaneous coronary intervention (PCI) is scheduled according to the current relevant treatment guidelines, tenecteplase should not be given' (§4.4); patients who cannot undergo primary PCI within one hour and receive tenecteplase 'should be transferred without delay to a coronary intervention capable facility for angiography and timely adjunctive coronary intervention within 6‑24 hours or earlier if medically indicated'. ADJUNCTIVE THERAPY (§4.2): antithrombotic adjunctive therapy with platelet inhibitors and anticoagulants 'should be administered according to the current relevant treatment guidelines'; unfractionated heparin and enoxaparin were used in clinical studies; 'Acetylsalicylic acid should be initiated as soon as possible after symptom onset and continued with lifelong treatment unless it is contraindicated.' The SPC gives no numeric dose for these adjuncts. PAEDIATRICS: §4.2 'The safety and efficacy of Metalyse in children (below 18 years) have not been established. No data are available' — hence paedDose is null.

Dose adjustments

Renal

Not stated — the fetched UK SPC §4.2 contains no renal-impairment subsection and gives no renal dose adjustment; the US TNKase sections fetched give none either. No renal dose reduction can be quoted from this bundle.

Hepatic

No dose adjustment is stated. Severe hepatic dysfunction is instead an absolute contraindication: §4.3 lists 'Severe hepatic dysfunction, including hepatic failure, cirrhosis, portal hypertension (oesophageal varices) and active hepatitis'.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — 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, or to gentamicin (a trace residue from the manufacturing process) (§4.3)
  • Significant bleeding disorder either at present or within the past 6 months
  • Patients receiving effective oral anticoagulant treatment (e.g. vitamin K antagonists with INR > 1.3)
  • Any history of central nervous system damage (i.e. neoplasm, aneurysm, intracranial or spinal surgery)
  • Known haemorrhagic diathesis
  • Severe uncontrolled hypertension
  • Major surgery, biopsy of a parenchymal organ, or significant trauma within the past 2 months (including any trauma associated with the current AMI)
  • Recent trauma to the head or cranium
  • Bacterial endocarditis, pericarditis
  • Acute pancreatitis
  • Severe hepatic dysfunction, including hepatic failure, cirrhosis, portal hypertension (oesophageal varices) and active hepatitis
  • Active ulcerative gastro-intestinal disease
  • Known arterial aneurysm and/or arterial/venous malformation
  • Neoplasm with increased bleeding risk
  • Any known history of haemorrhagic stroke or stroke of unknown origin
  • Known history of ischaemic stroke or transient ischaemic attack in the preceding 6 months
  • Dementia

Side effects

  • Haemorrhage — very common (≥1/10); 'The type of haemorrhage is predominantly superficial at the injection site' (§4.8)
  • Injection site haemorrhage and puncture site haemorrhage — common (≥1/100 to <1/10)
  • Ecchymosis — common; 'usually do not require any specific action'
  • Epistaxis — common
  • Gastrointestinal haemorrhage (gastric haemorrhage, gastric ulcer haemorrhage, rectal haemorrhage, haematemesis, melaena, mouth haemorrhage) — common
  • Urogenital haemorrhage (haematuria, haemorrhage urinary tract) — common
  • Intracranial haemorrhage (cerebral haemorrhage, cerebral haematoma, haemorrhagic stroke, haemorrhagic transformation stroke, intracranial haematoma, subarachnoid haemorrhage), with associated somnolence, aphasia, hemiparesis, convulsion — uncommon (≥1/1,000 to <1/100)
  • Reperfusion arrhythmias (asystole, accelerated idioventricular arrhythmia, extrasystoles, atrial fibrillation, AV block first degree to complete, bradycardia, tachycardia, ventricular arrhythmia, ventricular fibrillation, ventricular tachycardia) — uncommon; 'occur in close temporal relationship to treatment with tenecteplase'
  • Eye haemorrhage; retroperitoneal haemorrhage — uncommon
  • Anaphylactoid reaction including rash, urticaria, bronchospasm, laryngeal oedema — rare (≥1/10,000 to <1/1,000)
  • Pericardial haemorrhage; pulmonary haemorrhage; embolism (thrombotic embolisation); blood pressure decreased — rare
  • Nausea, vomiting; body temperature increased; fat embolism — frequency not known
  • 'Death and permanent disability are reported in patients who have experienced stroke (including intracranial bleeding) and other serious bleeding episodes' (§4.8)

Monitoring

  • Prescribing/setting: 'Metalyse should be prescribed by physicians experienced in the use of thrombolytic treatment and with the facilities to monitor that use' (§4.2).
  • Traceability: 'the trade name and the batch number of the administered product should be clearly recorded' (§4.4).
  • Bleeding: thrombolytic therapy 'requires careful attention to all possible bleeding sites (including catheter insertion sites, arterial and venous puncture sites, cutdown sites and needle puncture sites)'
  • avoid rigid catheters, intramuscular injections and non-essential handling of the patient during treatment.
  • If serious bleeding occurs (in particular cerebral haemorrhage) stop concomitant heparin immediately
  • 'Administration of protamine should be considered if heparin has been administered within 4 hours before the onset of bleeding'
  • consider cryoprecipitate, fresh frozen plasma and platelets with clinical and laboratory reassessment after each administration — 'A target fibrinogen level of 1 g/L is desirable with cryoprecipitate infusion.' Higher-risk groups to weigh against benefit (§4.4): systolic blood pressure >160 mmHg, GI or genitourinary bleeding within the past 10 days, recent intramuscular injection or small recent trauma, puncture of major vessels, age ≥75 years, body weight <50 kg.
  • US label: keep anti-arrhythmic therapy for bradycardia and/or ventricular irritability available
  • monitor for hypersensitivity during and for several hours after administration
  • during therapy 'results of coagulation tests and/or measures of fibrinolytic activity may be unreliable' because tenecteplase remains active in vitro and degrades fibrinogen in the sample.

Clinical monograph

How it works

It is a genetically modified, fibrin-specific tissue plasminogen activator that binds fibrin within the thrombus and converts plasminogen to plasmin, dissolving the clot; its modifications give greater fibrin specificity and a longer half-life allowing single-bolus dosing.

Prescribing in practice

  • Major bleeding, including intracranial haemorrhage, is the critical risk — screen carefully for absolute contraindications such as recent stroke, active internal bleeding, recent major surgery or trauma, and uncontrolled severe hypertension before giving.
  • It is dosed by body weight and given as a single rapid bolus; for STEMI it is combined with antithrombotic therapy, and the labelled dose differs from that used in acute ischaemic stroke protocols.
  • Concurrent anticoagulants and antiplatelets increase bleeding risk, so co-therapy and access-site management must follow the relevant reperfusion protocol.

Monitoring

Monitor for bleeding, neurological status, blood pressure, cardiac rhythm including reperfusion arrhythmias, and the ECG response to reperfusion.

Counselling the patient

  • Explain this clot-busting injection is given urgently to restore blood flow.
  • Report any new headache, weakness or bleeding immediately.
  • Bruising and minor bleeding at puncture sites are expected.

Evidence & guidelines

Single-bolus efficacy and safety in STEMI are supported by the ASSENT trial programme; pulmonary embolism use is supported by trials such as PEITHO and reflected in resuscitation and ESC guidance.

Reference: ASSENT-2 Trial (NEJM 1999); ESC STEMI Guidelines 2023; MHRA SPC Metalyse; NICE NG185 (VTE); ESC PE Guidelines 2019; 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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