Tissue Plasminogen Activator (TPA) Overview
Tissue Plasminogen Activator (TPA) initiates the breakdown of blood clots by
binding to fibrin within a clot and converting the entrapped plasminogen into
plasmin. This process leads to clot dissolution and is crucial in managing
thrombus formation conditions.
Types of TPA
There are three main types of TPA,
- Alteplase: A naturally occurring human plasminogen activator used for
treating ischemic stroke, myocardial infarction with ST-elevation (STEMI),
massive pulmonary embolism, and central venous device management. - Reteplase: A modified version of human TPA, it has a faster onset and longer
duration of action than Alteplase. It is FDA-approved for treating acute
myocardial infarction and is favoured over Alteplase because it has a longer
half-life, allowing administration as a bolus injection instead of an infusion. - Tenecteplase: Primarily used in the management of acute myocardial
infarction, Tenecteplase is a thrombolytic agent with a preference for this
condition.
Indications for TPA Use
- Ischemic stroke
- Myocardial infarction
- Pulmonary embolism
- Deep vein thrombosis (DVT)
TPA Administration Protocols
Administration of Alteplase
- For Acute Ischemic Stroke
- Dose: 0.9 mg/kg IV (maximum 90 mg total dose)
- Initial 10% given as an IV bolus over 1 minute, followed by the remaining
90% over 60 minutes. - Administration should occur within 3 hours of symptom onset, or up to 4.5
hours as recommended by the AHA.
2. For Acute Myocardial Infarction (MI)
- Administer as early as possible after symptom onset.
– Accelerated infusion (1.5 hours)
- Patients <67 kg: 15 mg IV bolus over 1–2 minutes, followed by 0.75 mg/kg
IV over 30 minutes (max 50 mg), then 0.5 mg/kg over the next 60 minutes (max35 mg). - Patients >67 kg: 15 mg IV bolus over 1–2 minutes, followed by 50 mg IV
infusion over 30 minutes, then the remaining 35 mg over 60 minutes.
– 3-hour infusion protocol
- Patients <65 kg: 0.075 mg/kg IV bolus, followed by 0.675 mg/kg over the
next hour, then 0.25 mg/kg for the remaining 2 hours. - Patients ≥65 kg: 6–10 mg IV bolus, followed by 50–54 mg in the first hour,
and 20 mg per hour over the next 2 hours.
3. For Pulmonary Embolism
- 100 mg IV over 2 hours.
- Parenteral anticoagulation should be started near the end or immediately
after the infusion when activated partial thromboplastin time (aPTT) or
thrombin time normalizes to less than twice the standard value.
4. For Arterial Thrombosis and Embolism
- Administer 0.05–0.1 mg/kg/hour by transcatheter intra-arterial infusion over
1–8 hours, or until thrombus-lysis is achieved.
Administration of Reteplase - Used in acute myocardial infarction treatment.
- Dose: 10 units IV bolus over 2 minutes, followed by a second dose 30 minutes
after the first (total of 20 units).
Administration of Tenecteplase - Weight-based IV bolus for acute myocardial infarction:
- <60 kg: 30 mg
- 60–70 kg: 35 mg
- 70–80 kg: 40 mg
- 80–90 kg: 45 mg
- >90 kg: 50 mg
