Calculate tPA (alteplase) dosing for acute ischemic stroke (0.9 mg/kg) and massive PE (100 mg). Includes bolus/infusion split, contraindication screening, time window check, and ICH risk estimate.
Tissue plasminogen activator (tPA, alteplase) is the only FDA-approved thrombolytic for acute ischemic stroke and is also used in massive pulmonary embolism. For stroke, the door-to-needle time goal is under 60 minutes, making rapid and accurate dosing essential. The stroke dose is weight-based (0.9 mg/kg, maximum 90 mg), with 10% given as an IV bolus over 1 minute and the remaining 90% infused over 60 minutes.
The decision to administer tPA balances the benefit of clot dissolution and neurological recovery against the 6% risk of symptomatic intracranial hemorrhage (sICH). This benefit-to-risk ratio is strongly time-dependent: treatment within 90 minutes of onset has the highest benefit, efficacy declines progressively through the 3-hour standard window and 4.5-hour extended window, and beyond 4.5 hours the risk exceeds the benefit for most patients.
This calculator computes the precise bolus and infusion doses, screens for major contraindications (blood pressure, glucose, time window, age-specific extended window restrictions), estimates ICH risk based on clinical variables, and provides a step-by-step administration protocol. For PE, the standard 100 mg dosing regimen is included with its different administration schedule.
Rapid and accurate tPA dosing is critical in stroke care where "time is brain" — every minute of delay results in ~1.9 million neurons lost. Mathematical errors under time pressure are common and potentially fatal. This calculator provides instant weight-based dosing with bolus/infusion separation, contraindication screening, and a structured protocol — supporting the door-to-needle time goal of under 60 minutes.
Stroke: Total dose = 0.9 mg/kg (max 90 mg) Bolus = 10% of total dose, IV push over 1 min Infusion = 90% of total dose, IV over 60 min PE: Total dose = 100 mg (10 mg bolus + 90 mg over 2 hours)
Result: Total: 72 mg (7.2 mg bolus + 64.8 mg infusion over 60 min)
80 kg × 0.9 mg/kg = 72 mg total. Bolus: 72 × 0.10 = 7.2 mg IV push over 1 minute. Infusion: 72 - 7.2 = 64.8 mg IV over 60 minutes. Within 3-hour window. SBP 172 is within limits (< 185). No flagged contraindications.
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Stroke uses 0.9 mg/kg (max 90 mg) based on the NINDS trial — this lower dose provides effective clot lysis with acceptable ICH risk in the brain. PE uses 100 mg (fixed dose) because pulmonary arteries are more tolerant of bleeding and the clot burden is typically larger. STEMI doses vary by protocol.
The ECASS III trial (2008) showed benefit up to 4.5 hours for selected patients. However, those >80 years old, NIHSS >25, on oral anticoagulants, or with diabetes + prior stroke are excluded from the extended window. Between 3-4.5 hours, benefit is modest but still significant.
Tenecteplase (TNK) is increasingly used off-label for stroke due to its single-bolus administration (faster), longer half-life, and emerging trial data (TRACE-2, AcT). The dose is 0.25 mg/kg single bolus. Some institutions have switched from alteplase to tenecteplase for stroke.
BP must be controlled to <185/110 BEFORE tPA. Labetalol 10-20 mg IV or nicardipine infusion are first-line agents. If BP cannot be controlled, tPA is contraindicated. Post-tPA, maintain BP <180/105 for 24 hours.
For large vessel occlusion (LVO) strokes, mechanical thrombectomy is indicated up to 24 hours (with perfusion imaging selection). tPA should still be given if within the window — do not delay tPA to assess thrombectomy eligibility. "Drip and ship" or "bridging" is the standard approach.
Several scoring systems predict symptomatic ICH: SEDAN, HAT, SITS-SICH. Risk factors include hyperglycemia (>144 mg/dL), high NIHSS (>10), age >75, uncontrolled hypertension, and extent of early ischemic changes on CT. Average sICH rate in trials is about 6% vs 0.6% for placebo.