Outputs Explained

After entering the required patient information, the calculator provides a clear summary of the recommended dosing protocol, including:

• Total Dose: The full amount of alteplase to be administered for the entire treatment course, adjusted for weight and maximum dose limits where applicable.
• Bolus Dose: The initial dose to be administered rapidly, typically over one minute. The output provides this in both milligrams (mg) and milliliters (mL), assuming a standard 1 mg/mL concentration.
• Infusion Dose: The remaining portion of the total dose to be administered via continuous infusion. This is also provided in mg and mL.
• Infusion Rate: The calculated rate for the infusion pump, expressed in mL/hour, to ensure the dose is delivered over the correct duration (e.g., 60 minutes for stroke, or 30 and 60-minute infusions for STEMI).

How to Use the Tool

1. Select Clinical Indication: Choose the reason for administration from the available options: Acute Ischemic Stroke, STEMI, Massive PE, or Catheter Clearance.
2. Enter Patient Weight: For weight-based indications (Stroke, STEMI), input the patient’s weight. Use the toggle to switch between kilograms (kg) and pounds (lbs).
3. Review Contraindications: It is highly recommended to review the contraindication checklist to ensure patient safety before proceeding.
4. Calculate Dose: Click the “Calculate Dose” button to generate the dosing regimen.
5. Verify Results: The tool will display the complete, step-by-step dosing instructions. All calculated values must be independently verified by a qualified healthcare professional before medication preparation and administration.

Dosing Overview

Alteplase dosing varies significantly by indication. The calculator implements the following standard protocols:

Acute Ischemic Stroke (AIS)

The total dose is 0.9 mg/kg, with a maximum total dose of 90 mg. The administration is split into a bolus and an infusion:

• Bolus: 10% of the total dose is given as an IV push over 1 minute.
• Infusion: The remaining 90% is infused intravenously over 60 minutes.

STEMI (Accelerated Infusion)

The total dose should not exceed 100 mg and is administered in three parts:

• Bolus: A 15 mg IV bolus is given initially.
• Infusion 1 (30 minutes): For patients >67 kg, 50 mg is infused. For patients ≤67 kg, a dose of 0.75 mg/kg (up to 50 mg) is infused.
• Infusion 2 (60 minutes): Following the first infusion, patients >67 kg receive 35 mg. Patients ≤67 kg receive 0.5 mg/kg (up to 35 mg).

Massive Pulmonary Embolism (PE)

A fixed, non-weight-based dose of 100 mg is administered as a continuous intravenous infusion over 2 hours.

Occluded Central Venous Catheter (Cathflo®)

A 2 mg dose is instilled into the dysfunctional catheter. This dose may be repeated once if catheter function is not restored after a 30-120 minute dwell time.

Switching Medications

This section is not applicable. Alteplase is a thrombolytic agent used for acute, life-threatening events. It is not a maintenance medication. Following its administration, patients are typically transitioned to anticoagulant or antiplatelet therapies based on the clinical indication and institutional protocols. Treatment decisions must be guided by a qualified physician.

Missed Dose

This section is not applicable. The administration of alteplase is a single, time-critical intervention performed under direct medical supervision. The entire bolus and infusion schedule must be adhered to precisely. Any interruption in the infusion should be addressed immediately by the clinical team, as it can significantly impact therapeutic efficacy.

Safety Alerts

Alteplase carries a significant risk of bleeding, which can be severe and potentially fatal. It is contraindicated in numerous conditions. The most critical considerations include:

• Active Bleeding: Do not administer to patients with active internal bleeding.
• Intracranial Hemorrhage (ICH): Exclude ICH with a non-contrast head CT before administration for stroke. Contraindicated in patients with a history of recent ICH.
• Recent Stroke or Head Trauma: Contraindicated if the patient has had an ischemic stroke, severe head trauma, or intracranial/intraspinal surgery within the last 3 months.
• Uncontrolled Hypertension: Blood pressure must be controlled (e.g., SBP <185 mmHg and DBP <110 mmHg for stroke) before and during treatment to reduce the risk of ICH.
• Bleeding Diathesis: Use with extreme caution in patients with known coagulation defects or those on concurrent anticoagulants.

This is not an exhaustive list of contraindications or warnings. Always consult the official prescribing information and institutional protocols before use.

Frequently Asked Questions

What is the maximum dose of Alteplase for ischemic stroke?

The total dose for acute ischemic stroke is capped at 90 mg, regardless of whether the patient’s weight-based calculation (0.9 mg/kg) exceeds this amount.

How is the STEMI dose different for patients weighing 67 kg or less?

For patients ≤67 kg, the two infusion portions of the accelerated regimen are weight-based (0.75 mg/kg for the first 30 mins and 0.5 mg/kg for the next 60 mins), with maximums of 50 mg and 35 mg, respectively. The initial 15 mg bolus remains the same for all patients.

Does the calculator use a specific Alteplase concentration?

Yes, all volume calculations (in mL) are based on a standard reconstituted concentration of 1 mg/mL.

Is the dose for massive PE based on patient weight?

No, the approved regimen for massive pulmonary embolism is a fixed 100 mg dose infused over 2 hours and is not adjusted for patient weight.

What is Cathflo Activase used for?

Cathflo Activase is a 2 mg formulation of alteplase used specifically for restoring function to occluded central venous access devices (CVADs). It is not for systemic administration.

Why is there a contraindication checklist in the tool?

The checklist serves as a critical safety reminder to review key factors that could make alteplase administration dangerous or harmful. Selecting an absolute contraindication generates a prominent warning.

Can I use this calculator for other thrombolytics like tenecteplase?

No. This calculator is designed exclusively for alteplase (Activase). Dosing for other thrombolytic agents like tenecteplase is different and requires a separate protocol.

What is the importance of the “Last Known Well” time for ischemic stroke?

The “Last Known Well” time is crucial for determining if a patient is within the therapeutic window for receiving alteplase, which is typically within 3 to 4.5 hours of symptom onset for most patients. This field is for reference and does not alter the dose calculation.

References

1. Activase® (alteplase) Prescribing Information. Genentech, Inc. U.S. Food and Drug Administration. Revised 2018.
2. Cathflo® Activase® (alteplase) Prescribing Information. Genentech, Inc. U.S. Food and Drug Administration. Revised 2015.
3. Activase® (alteplase) for Injection Official HCP Site. Genentech USA, Inc.
4. Powers WJ, et al. 2019 Update to the 2018 Guidelines for the Early Management of Acute Ischemic Stroke. Stroke. 2019;50:e344–e418.