Free tPA Calculator - Stroke Dosing

The tPA (tissue plasminogen activator) dosage calculator helps clinicians quickly verify the appropriate alteplase dose for stroke patients. This tool uses the standard weight-based protocol to compute both the bolus and infusion components of IV tPA therapy, ensuring accurate dosing in acute ischemic stroke.

Understanding tPA (Tissue Plasminogen Activator)

tPA is a naturally occurring enzyme in the bloodstream that plays a key role in dissolving blood clots. It works by converting the inactive precursor plasminogen into active plasmin, an enzyme that breaks down fibrin clots—a process called fibrinolysis. Alteplase is a recombinant form of this protein (rtPA) produced through biotechnology. In cases where rapid reversal of its fibrinolytic effect is needed, aminocaproic acid serves as the antidote.

Indications for tPA Treatment

Tissue plasminogen activators are used to treat several thromboembolic conditions. The most common indication is acute ischemic stroke, but they are also employed in myocardial infarction (heart attack), pulmonary embolism, thrombosis of prosthetic heart valves or peripheral arteries, frostbite, and pleural effusion secondary to pneumonia. It is important to note that tPA dosing for stroke differs significantly from dosing for other indications; this calculator focuses specifically on the stroke protocol.

Routes of Administration

tPA can be delivered via multiple routes, though intravenous (IV) injection is the standard for stroke. Other administration methods include intracatheter (directly into a catheter), intra-hemodialysis catheter, intra-arterial (off-label, used for frostbite or arterial occlusion), and intrapleural (instilled between the pleural layers). The IV route is the basis for the dosing calculations used in this tool.

Recommended Dosing Regimen for Acute Stroke

The established dosing protocol for alteplase in acute stroke follows a weight-based scheme:

• Recommended total dose: 0.9 mg/kg (maximum of 90 mg)
• Bolus component: 10% of the total dose given as an IV push over 1 minute
• Infusion component: 90% of the total dose delivered as a continuous IV infusion over 60 minutes

The dosing steps differ depending on the patient's weight:

• Weight < 100 kg: Bolus = 0.09 mg/kg (or 10% of 0.9 mg/kg); Infusion = 0.81 mg/kg (or 90% of 0.9 mg/kg)
• Weight ≥ 100 kg: Bolus = 9 mg; Infusion = 81 mg (this caps the total dose at 90 mg)

Calculating the tPA Dose

The formula for the total IV dose of alteplase is straightforward:

To illustrate, consider a 70 kg patient presenting with acute stroke symptoms:

This 63 mg total is then split into a bolus of 6.3 mg (administered over 1 minute) and an infusion of 56.7 mg (given over the following 60 minutes).

Important Clinical Notes

This calculator serves as a secondary check and should not replace independent clinical decision‑making. Always confirm the calculated dose with local protocols and consult a physician if there is any uncertainty. The tPA stroke dosing regimen is time‑sensitive; adherence to the correct weight‑based protocol helps maximize the benefit‑risk balance for the patient.