tPA Stroke Dosing Calculator
Alteplase and Tenecteplase dose calculator for acute ischemic stroke — for clinical verification only
Clinical Decision Support Tool
This calculator is intended to assist qualified healthcare professionals in verifying tPA dosing. It is NOT a substitute for clinical judgment, institutional protocols, or independent dose verification. Always confirm calculations with a second clinician and follow your institution's stroke protocol.
Select the thrombolytic agent or compare both side-by-side
Weight used for dose calculation — affects total dose and cap eligibility
Used to assess treatment window eligibility (0–3 hr standard; 3–4.5 hr extended for alteplase)
Pre-Treatment Eligibility Checklist
Confirm all required criteria are met before proceeding
Enter Patient Weight to Calculate Dose
Enter the patient weight above to calculate alteplase and tenecteplase doses for acute ischemic stroke.
How to Use the tPA Stroke Dosing Calculator
Select Thrombolytic Agent and Enter Patient Weight
Choose alteplase (tPA), tenecteplase (TNK), or both for side-by-side comparison. Enter the patient weight in kg or lbs. The calculator automatically converts lbs to kg and applies the weight-based formula with the appropriate dose cap (90 mg for alteplase, 25 mg for tenecteplase).
Enter Time Since Symptom Onset
Enter the hours and minutes since the patient's last known well or symptom onset. The calculator displays a color-coded treatment window indicator: standard window (0–3 hours), extended window (3–4.5 hours, alteplase with ECASS III criteria only), or outside standard window (greater than 4.5 hours). This guides eligibility assessment.
Review Doses and Administration Parameters
Review the calculated total dose, bolus dose and volume, infusion dose and rate (for alteplase), or single bolus volume (for tenecteplase), and waste discard volume. All volumes are based on standard reconstitution concentrations (1 mg/mL for alteplase, 5 mg/mL for tenecteplase). Verify independently before administration.
Use Post-Administration Monitoring Schedule and Copy Summary
After dose calculation, review the post-administration BP and neurological monitoring schedule, the antithrombotic hold guidance, and the follow-up CT timing. Use the Copy Summary button to generate a text summary of all dosing parameters for documentation in the patient chart or handoff communication.
Frequently Asked Questions
What is the correct alteplase dose for acute ischemic stroke?
The FDA-approved alteplase dose for acute ischemic stroke is 0.9 mg/kg with an absolute maximum of 90 mg, regardless of patient weight. Ten percent of the total dose (0.09 mg/kg) is given as an IV bolus over exactly 1 minute, and the remaining 90% (0.81 mg/kg) is infused over 60 minutes via an IV pump. The drug is reconstituted in a 100 mg vial with 100 mL of sterile water to produce a 1 mg/mL solution, so dose in milligrams equals dose volume in milliliters. Never use the STEMI alteplase protocol (100 mg fixed dose) for stroke — this error has caused fatal hemorrhagic transformations. Always cap at 90 mg and verify the calculation with a second clinician.
How does tenecteplase dosing differ from alteplase for stroke?
Tenecteplase (TNK) for acute ischemic stroke is dosed at 0.25 mg/kg with a maximum of 25 mg, compared to alteplase at 0.9 mg/kg with a maximum of 90 mg. The key practical difference is administration: tenecteplase is given as a single IV bolus over just 5 seconds, while alteplase requires a 1-minute bolus followed by a 60-minute infusion. Tenecteplase's simplified protocol may reduce preparation time and potential for administration errors. It has 8 to 10 times greater fibrin specificity than alteplase. The standard vial concentration for tenecteplase is 5 mg/mL, so the dose volume in mL equals the dose in mg divided by 5. Tenecteplase is FDA-approved for stroke within 3 hours of symptom onset.
What are the absolute contraindications to tPA in stroke?
Absolute contraindications mean tPA must NOT be administered and include: intracranial hemorrhage visible on CT, active internal bleeding, blood pressure persistently above 185/110 mmHg despite antihypertensive treatment, DOAC use within the past 48 hours, warfarin use with INR above 1.7 or PT above 15 seconds, platelet count below 100,000 per microliter, prior history of intracranial hemorrhage, known intracranial neoplasm or arteriovenous malformation or aneurysm, head trauma or prior ischemic stroke within the past 3 months, and clinical presentation suggesting subarachnoid hemorrhage even if CT is negative. These contraindications apply to all treatment windows and both alteplase and tenecteplase.
What is the 3 to 4.5 hour extended treatment window for alteplase?
The extended treatment window from 3 to 4.5 hours after symptom onset applies only to alteplase, not tenecteplase, and is considered off-label (supported by ECASS III trial evidence). For patients in this window, all of the following criteria must be met: NIHSS score must be 25 or below, the patient must be age 80 or under, there must be no combined history of both prior stroke and diabetes mellitus, no oral anticoagulant use regardless of INR, and imaging must not show involvement of more than one-third of the middle cerebral artery territory. The evidence level is Class IIa under AHA/ASA guidelines. Patients meeting these criteria may benefit significantly from treatment, and the risk of withholding treatment should be weighed carefully against hemorrhage risk.
What monitoring is required after tPA administration?
Post-tPA monitoring is intensive and must continue for 24 hours. Blood pressure and neurological status are assessed every 15 minutes for the first 2 hours, every 30 minutes from hours 2 to 8, and hourly from hours 8 to 24. The blood pressure target is 180/105 mmHg or below for the first 24 hours. All antithrombotics, including aspirin, clopidogrel, heparin, and anticoagulants, must be held for at least 24 hours. A follow-up head CT or MRI must be obtained at 24 hours before any antithrombotic can be resumed. Watch closely for symptomatic intracranial hemorrhage: sudden neurological deterioration, new severe headache, nausea, vomiting, or acute hypertension are warning signs requiring immediate head CT and neurosurgical consultation.
Why is weight-based dosing so important for tPA in stroke?
Weight-based dosing ensures patients receive a therapeutically effective dose while minimizing hemorrhage risk. The alteplase dose of 0.9 mg/kg was established through clinical trials that balanced thrombolytic efficacy against the risk of symptomatic intracranial hemorrhage, which occurs in approximately 6% of treated patients. Overdosing — even by a small margin — significantly increases hemorrhage risk, while underdosing may reduce clot lysis effectiveness. The 90 mg cap protects heavier patients from receiving a potentially dangerous total dose. For this reason, accurate patient weight is essential, and estimated weights should only be used if measured weight is unavailable. Some institutions use lean body weight for very obese patients, though the standard protocol uses total body weight. Always follow your institutional protocol for weight estimation in emergency scenarios.