tPA Calculator – Stroke Dosing

By Łucja Zaborowska, MD
Last updated: Mar 18, 2021

The tPA calculator double-checks the correct dose of alteplase needed for your stroke patients.

In the article below, we'll teach you how to calculate the tPA dose for a stroke - we'll also talk about possible alteplase antidote and present the basic rules of tPA administration. 💉

❗ Remember, our tool cannot be used as the one and only source of clinical knowledge - always double-check your calculations or consult a more experienced physician.

What is alteplase – tPA?

tPA stands for the tissue plasminogen activator - a kind of enzyme present in our blood vessels, responsible for dissolving blood clots and maintaining a liquidity of our blood.

Alteplase is a recombinant, man-made version of this protein (rtPA). To reverse its toxicity effects in case of an emergency, we usually use the alteplase antidote: aminocaproic acid.

How does alteplase and tPA work?

tPA works by triggering the conversion of inactive plasminogen to active plasmin. Plasmin works by dissolving the fibrin clots in our bloodstream - this process is called fibrinolysis.

tPA calculator and alteplase calculator

We usually use the tissue plasminogen activators to treat:

  • Stroke (remember - tPA doses for stroke and other diseases are entirely different);
  • Heart attack 💔;
  • Pulmonary embolism;
  • Thrombosis of an artificial valve /peripheral artery;
  • Frostbites; and
  • Pleural effusion cased by pneumonia.
💡 An enzyme is a kind of active protein that's capable of triggering different chemical reactions in organisms. You may find out more using our enzyme kinetics tool.

How is tPA administered?

We can perform tPA administration in a variety of ways:

  • Intravenously (IV) - into the vein;
  • Intracatheter - into the catheter;
  • Intra-hemodialysis catheter - into the hemodialysis catheter;
  • Intra-arterial (off-label) - might be used in a case of a frostbite or arterial occlusion; and
  • Intrapleural - between the pleurae, membranes that surround lungs and the chest cavity.

We usually administer tPA intravenously - that's the foundation our alteplase calculator is based on.

💡 Recommended dosage: 0.9 mg/kg
Maximum dosage: 90 mg

  1. If our patient weights <100 kg: ⬇️

    • During the first 1 minute:
      • IV bolus
      • 10% of recommended dose (0.09 mg/kg)
    • During the next 60 min
      • IV continuous infusion
      • 90% of recommended dose (0.81 mg/kg)
  2. If our patient weights ≥100 kg: ⬆️

    • During the first 1 minute:
      • IV bolus
      • 9 mg
    • During the next 60 min
      • IV continuous infusion
      • 81 mg

How to calculate tPA dose?

tPA dosage for stroke should be calculated using the patient's weight. That's why we shouldn't use the tPA dosing charts since they might be not as accurate as we want them to be.

Our alteplase calculator uses the following equation, based on the recommended IV (intravenous) dose:

💡 Maximum dosage allowed: 90 mg

Dosage IV (mg) = 0.9 * Weight (kg),

where:

  • Dosage IV is given in milligrams (mg); and
  • Weight should be given in kilograms (try our weight converter).

tPA calculation example:

Our patient is a male with acute stroke symptoms. He weighs 70 kg.

Dosage IV = 0.9 * 70 kg

Dosage IV = 63 mg

We should administer 63 mg of tPA intravenously. 👍

Łucja Zaborowska, MD
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