What are the recommended fibrinolytic drug dosages, including aspirin and anticoagulation, for an adult STEMI patient with no contraindications?

Fibrinolytic Drug Dosages for STEMI

For adult STEMI patients without contraindications, administer one of three fibrin-specific agents: Tenecteplase as a single weight-based IV bolus (30-50 mg), Reteplase as two 10-unit IV boluses 30 minutes apart, or Alteplase as a 90-minute weight-based infusion (up to 100 mg total). 1

Specific Fibrinolytic Dosing

Tenecteplase (TNK-tPA) - Preferred Agent

• <60 kg: 30 mg single IV bolus
• 60-69 kg: 35 mg single IV bolus
• 70-79 kg: 40 mg single IV bolus
• 80-89 kg: 45 mg single IV bolus
• ≥90 kg: 50 mg single IV bolus 1

Reteplase (rPA)

• 10 units IV bolus administered over 2 minutes
• Second 10 units IV bolus given 30 minutes after the first 1

Alteplase (tPA)

For patients ≥67 kg:

• 15 mg IV bolus
• Then 50 mg IV infused over 30 minutes
• Then 35 mg IV infused over next 60 minutes
• Total dose: 100 mg maximum

For patients <67 kg:

• 15 mg IV bolus
• Then 0.75 mg/kg IV (not exceeding 50 mg) over 30 minutes
• Then 0.5 mg/kg IV (not exceeding 35 mg) over 60 minutes 1

Mandatory Adjunctive Antiplatelet Therapy

Aspirin

• Loading dose: 162-325 mg orally (chewed, non-enteric coated) 2, 3, 4
• Maintenance: 75-100 mg daily indefinitely 4
• If oral route unavailable, use 250 mg IV 5

Clopidogrel

Age ≤75 years:

• Loading dose: 300 mg orally 2, 3
• Maintenance: 75 mg daily for at least 14 days, up to 1 year 2, 3

Age >75 years:

• No loading dose - start with 75 mg orally 2, 3
• Maintenance: 75 mg daily for at least 14 days, up to 1 year 2, 3

Mandatory Adjunctive Anticoagulation

Choose ONE of the following regimens for minimum 48 hours, preferably until discharge (up to 8 days) or revascularization: 2, 3

Enoxaparin (Preferred over UFH)

Age <75 years:

• 30 mg IV bolus
• Then 1 mg/kg subcutaneous every 12 hours starting 15 minutes after bolus
• Maximum 100 mg for first 2 doses

Age ≥75 years:

• No IV bolus
• 0.75 mg/kg subcutaneous every 12 hours
• Maximum 75 mg for first 2 doses

Creatinine clearance <30 mL/min (any age):

• 1 mg/kg subcutaneous every 24 hours 2, 3

Unfractionated Heparin (UFH)

• IV bolus: 60 units/kg (maximum 4000 units)
• IV infusion: 12 units/kg/hour (maximum 1000 units/hour)
• Target aPTT: 1.5-2.0 times control (approximately 50-70 seconds)
• Monitor aPTT at 3,6,12, and 24 hours 2, 5

Fondaparinux

• Initial dose: 2.5 mg IV
• Then: 2.5 mg subcutaneous daily starting next day
• Only if creatinine clearance >30 mL/min 2, 3

Critical Timing Considerations

Fibrinolytic therapy must be administered within 30 minutes of hospital arrival when indicated. 6 The benefit is greatest within the first 2 hours of symptom onset and diminishes progressively thereafter. 6 Fibrinolysis is indicated when symptoms began <12 hours ago and primary PCI cannot be performed within 120 minutes of first medical contact. 1, 2, 3

Important Caveats

• Streptokinase is no longer available in the United States 1
• Tenecteplase offers the advantage of single bolus administration, making it the most convenient option
• For patients with body weight >100 kg, consider measuring anti-Xa activity when using enoxaparin 7
• Do not use fondaparinux as sole anticoagulant if PCI is anticipated - add an agent with anti-IIa activity due to catheter thrombosis risk 8
• All patients should be transferred to a PCI-capable center after fibrinolysis for angiography between 2-24 hours if successful, or immediately for rescue PCI if fibrinolysis fails 9