Reteplase Dosing for Myocardial Infarction
Reteplase is administered as two 10-unit intravenous bolus injections given 30 minutes apart for the treatment of ST-elevation myocardial infarction (STEMI). 1
Standard Dosing Regimen
- First bolus: 10 units IV over 2 minutes 1, 2, 3
- Second bolus: 10 units IV over 2 minutes, given 30 minutes after the first bolus 1, 2, 3
- This is a non-weight-based regimen, making it simpler to administer than weight-adjusted alternatives like alteplase 2, 3
Timing and Indications
- Fibrinolytic therapy with reteplase is recommended within 12 hours of symptom onset when primary PCI cannot be performed by an experienced team within 120 minutes of first medical contact 1
- Pre-hospital administration should be considered when feasible to minimize time to treatment, as the ease of bolus dosing makes reteplase particularly suitable for this setting 1, 2, 3
- Greatest benefit occurs in patients presenting early (<2 hours) with large infarcts and low bleeding risk 1
Mandatory Adjunctive Therapy
Antiplatelet Agents
- Aspirin: 150-325 mg loading dose (chewed if oral, or 250 mg IV if oral route unavailable), followed by 75-160 mg daily 1
- Clopidogrel: 300 mg loading dose (for patients ≤75 years), followed by 75 mg daily 1
Anticoagulation (Required)
- Unfractionated heparin (UFH): 60 U/kg IV bolus (maximum 4000 U) followed by 12 U/kg/hour infusion (maximum 1000 U/hour) for 24-48 hours, targeting aPTT 50-70 seconds 1
- Enoxaparin (preferred over UFH): For patients <75 years: 30 mg IV bolus, then 1 mg/kg subcutaneous every 12 hours; For patients ≥75 years: no IV bolus, start with 0.75 mg/kg subcutaneous every 12 hours 1
- Anticoagulation should continue until revascularization or for duration of hospital stay, up to 8 days 1
Clinical Efficacy Evidence
Reteplase achieves superior early coronary patency compared to alteplase, with 60-minute TIMI 3 flow rates equivalent to alteplase at 90 minutes, though 35-day mortality rates are equivalent 1, 4. The 10+10 unit regimen produces 63% TIMI 3 flow at 90 minutes versus 49% with accelerated alteplase 4. Mortality equivalence with streptokinase has been demonstrated (9.02% vs 9.53% at 35 days), with similar bleeding rates but reduced cardiac complications 5.
Critical Post-Fibrinolysis Management
- All patients must be transferred to a PCI-capable center following fibrinolysis 1
- Rescue PCI is indicated immediately if fibrinolysis fails (<50% ST-segment resolution at 60 minutes) 1
- Routine angiography with view to revascularization is indicated 3-24 hours after successful fibrinolysis in stable patients 1
Important Safety Considerations
Absolute contraindications include: any prior intracranial hemorrhage, ischemic stroke within 6 months, active bleeding, aortic dissection, and severe uncontrolled hypertension (SBP >180 mmHg or DBP >110 mmHg) 1. Reteplase should not be re-administered if reocclusion occurs, as it can be given again (unlike streptokinase which causes persistent antibodies), though this increases bleeding risk 1. Intracranial hemorrhage rates are approximately 0.76-1.23%, similar to other fibrin-specific agents 2, 6, 5.