Alteplase Dosing for Acute Ischemic Stroke
The full loading dose of alteplase for acute ischemic stroke is 0.9 mg/kg (maximum 90 mg total), administered as 10% of the total dose given as an IV bolus over 1 minute, followed by the remaining 90% infused over 60 minutes. 1
Dosing Algorithm
Standard Dose Calculation
- Total dose: 0.9 mg/kg body weight
- Maximum dose: 90 mg (regardless of weight)
- Initial bolus: 10% of calculated dose over 1 minute
- Continuous infusion: Remaining 90% over 60 minutes
Example: For a 70 kg patient:
- Total dose = 70 kg × 0.9 mg/kg = 63 mg
- Bolus = 6.3 mg over 1 minute
- Infusion = 56.7 mg over 60 minutes
Time Windows
This dosing regimen applies to both approved time windows 1:
- 0-3 hours from symptom onset: Class I recommendation (Level of Evidence A)
- 3-4.5 hours from symptom onset: Class I recommendation (Level of Evidence B-R)
The 3-4.5 hour window has additional exclusion criteria: patients must be ≤80 years old, without both diabetes AND prior stroke, NIHSS ≤25, not on oral anticoagulants, and without imaging showing >1/3 MCA territory involvement 1.
Critical Pitfalls to Avoid
Do not use reduced dosing (0.6 mg/kg) in standard practice. While some research suggests 0.6 mg/kg may reduce symptomatic intracranial hemorrhage 2, the 0.9 mg/kg dose is the only FDA-approved and guideline-recommended regimen for acute ischemic stroke 1. Recent meta-analysis shows standard dosing maintains functional outcomes, and Bayesian analysis demonstrates that reduced-dose regimens do not show consistent efficacy 3.
Time is brain: Every minute of delay worsens outcomes. The guidelines emphasize initiating treatment "as quickly as possible" because time to treatment is strongly associated with outcomes 1. Do not delay for non-essential testing once eligibility is confirmed.
Pre-Treatment Requirements
Blood pressure must be safely lowered to <185/110 mmHg before initiating alteplase and maintained below this threshold during and after treatment 1. This is non-negotiable—the medication should not be given if BP cannot be controlled to these parameters.
Evidence Strength
The dosing recommendation comes from the 2018 AHA/ASA Guidelines, which represent the highest quality evidence available (Class I, Level A for the 0-3 hour window) 1. This dosing has been validated across multiple large randomized trials and remains the standard of care despite emerging alternatives like tenecteplase 4.