What is the loading dose for fibrinolysis using streptokinase?

Streptokinase Loading Dose for Fibrinolysis

The loading dose for fibrinolysis using streptokinase is 1.5 million units administered intravenously over 30-60 minutes. 1, 2

Dosing Details and Administration

Streptokinase is administered as:

• 1.5 million units total dose
• Delivered intravenously (IV)
• Infused over 30-60 minutes
• No weight-based adjustment required (fixed dose)

This dosing regimen has been established through clinical trials to provide effective thrombolysis while maintaining an acceptable safety profile. The European Society of Cardiology and American College of Cardiology guidelines consistently recommend this dosage 1, 2.

Efficacy

Streptokinase achieves 60-68% patency rates (TIMI 2 or 3 flow at 90 minutes) when administered at this dose 1. While this is lower than the patency rates achieved with fibrin-specific agents like alteplase (73-84%) or tenecteplase (85%), streptokinase remains clinically effective for fibrinolysis 1.

Important Considerations

Contraindications

• Absolute contraindication: Prior streptokinase exposure within the past 6 months due to high risk of serious allergic reactions 1, 2
• Streptokinase is highly antigenic, and antibodies persist for at least 10 years, impairing its activity and increasing risk of allergic reactions 2

Adjunctive Therapy

When administering streptokinase, the following adjunctive therapies should be given:

1. Antiplatelet therapy:

   • Aspirin: 150-500 mg orally (starting dose) or 250 mg IV if oral ingestion not possible 1
   • Clopidogrel: 300 mg loading dose if age ≤75 years, or 75 mg if age >75 years 1

2. Anticoagulation:

   • Unfractionated heparin: 60 U/kg IV bolus (maximum 4000 U) followed by IV infusion of 12 U/kg/hr (maximum 1000 U/hr) for 24-48 hours 1
   • Target aPTT: 50-70 seconds or 1.5-2.0 times control, monitored at 3,6,12, and 24 hours 1

Clinical Pitfalls to Avoid

1. Reuse in previously exposed patients: Never readminister streptokinase to patients with previous exposure, as antibodies persist for years 2

2. Bleeding risk: Monitor for bleeding complications, which occur more frequently with streptokinase than with fibrin-specific agents. In the GUSTO trial, bleeding complications were observed but major bleeding occurred in only 2.7% of patients undergoing rescue PCI after streptokinase 1

3. Hypotension: Streptokinase can cause hypotension during infusion; monitor blood pressure closely and slow the infusion rate if significant hypotension occurs

4. Timing: For optimal outcomes in STEMI, administer within 12 hours of symptom onset, with greatest benefit seen when given within the first 3 hours 1

By following these guidelines for streptokinase administration, you can optimize the efficacy while minimizing the risks associated with fibrinolytic therapy in appropriate patients.