About This Calculator

This Tenecteplase (TNK) Stroke Dose Calculator is designed to assist healthcare professionals in determining the appropriate dose of tenecteplase for patients with acute ischemic stroke. By inputting the patient’s weight, the tool calculates the total dose in milligrams and the corresponding volume to administer based on the standard concentration, adhering to current clinical guidelines.

Outputs Explained

The calculator provides two key outputs for safe and accurate administration:

• Total Dose (mg): The total mass of tenecteplase to be administered, calculated at 0.25 mg per kilogram of body weight, up to a maximum of 25 mg.
• Volume to Administer (mL): The volume of the reconstituted solution to draw up for the bolus injection. This is based on a standard final concentration of 5 mg/mL after reconstituting a 50 mg vial with 10 mL of Sterile Water for Injection (SWFI).

How to Use the Tool

Follow these simple steps to determine the correct tenecteplase dose:

1. Enter Patient Weight: Input the patient’s weight into the designated field.
2. Select Units: Use the toggle to select the correct unit of weight, either kilograms (kg) or pounds (lbs). The tool will automatically handle the conversion.
3. Calculate: Click the “Calculate Dose” button to generate the results. The tool will display the total dose and volume, applying the 25 mg maximum dose cap if necessary.

Dosing Overview

The dosing for tenecteplase in acute ischemic stroke is based on the 2019 AHA/ASA guidelines. The recommended regimen is:

• Dose: 0.25 mg/kg body weight.
• Maximum Dose: A single maximum dose of 25 mg is administered, regardless of whether the patient’s weight-based calculation exceeds this amount (i.e., for patients weighing >100 kg).
• Administration: The total calculated dose is given as a single intravenous (IV) bolus over 5 seconds. No subsequent infusion is required.

Switching Thrombolytics

This section is not applicable. Tenecteplase is administered as a single, one-time bolus for the treatment of acute ischemic stroke. Switching between different thrombolytic agents during an acute event is not a standard clinical practice and should not be done.

Missed Dose

This section is not applicable. As a thrombolytic agent used in an emergency setting, tenecteplase is administered as a single dose under direct medical supervision. The concept of a “missed dose” does not apply to this treatment regimen.

Safety Alerts and Contraindications

Tenecteplase is contraindicated in patients with conditions that increase the risk of bleeding. The decision to treat must follow a thorough risk-benefit assessment. Key contraindications include:

• Active internal bleeding
• History of intracranial hemorrhage
• Recent (within 3 months) serious head trauma, intracranial/intraspinal surgery, or stroke
• Intracranial conditions that increase bleeding risk (e.g., AVM, aneurysm, neoplasm)
• Known bleeding diathesis or current use of anticoagulants with elevated INR (>1.7)
• Severe uncontrolled hypertension

Frequently Asked Questions (FAQ)

1. What is the maximum dose of tenecteplase for stroke calculated by this tool?
   The calculator adheres to clinical guidelines, capping the maximum dose at 25 mg for any patient weighing 100 kg or more.
2. How does the calculator handle weight input in pounds (lbs)?
   When ‘lbs’ is selected, the tool automatically converts the weight to kilograms (kg) using the standard conversion factor (1 kg ≈ 2.20462 lbs) before calculating the dose.
3. What is the final concentration of tenecteplase after reconstitution?
   The standard reconstitution of a 50 mg vial with 10 mL of Sterile Water for Injection (SWFI) results in a final concentration of 5 mg/mL, which this calculator uses for its volume calculation.
4. Why does the tool provide both dose (mg) and volume (mL)?
   It provides the dose for clinical documentation and verification, and the volume for accurate preparation and administration of the IV bolus.
5. Can this calculator be used for other indications like myocardial infarction?
   No. This calculator is specifically configured for the acute ischemic stroke dosing regimen (0.25 mg/kg, max 25 mg) and should not be used for other approved indications, which have different dosing protocols.
6. What is the time window for administering tenecteplase in acute ischemic stroke?
   Tenecteplase is generally considered for eligible patients with symptom onset within 4.5 hours.
7. Does this tool account for pediatric or low-weight adult patients?
   The tool has a built-in validation range. It is intended for adults and will show an error for weights outside a typical clinical range (e.g., below 30 kg), as dosing in these populations may require specialist consultation.
8. Is this calculator a substitute for professional clinical judgment?
   Absolutely not. It is an informational tool to support clinical decision-making. All calculations must be independently verified, and treatment decisions must be based on a complete patient assessment and institutional protocols.

References

• Powers WJ, et al. 2019 Update to the 2018 Guidelines for the Early Management of Acute Ischemic Stroke: A Guideline for Healthcare Professionals From the American Heart Association/American Stroke Association. Stroke. 2019;50:e344–e418. View Guideline
• TNKase® (tenecteplase) Prescribing Information. Genentech, Inc. View Prescribing Information
• U.S. Food and Drug Administration (FDA). Drugs@FDA: TNKase (tenecteplase). View FDA Page
• European Medicines Agency (EMA). Metalyse (tenecteplase). View EMA Summary