Comparison of Streptokinase vs Urokinase for Thrombolytic Therapy
Urokinase is the superior thrombolytic agent compared to streptokinase due to its higher efficacy and better safety profile, despite its higher cost. 1, 2
Efficacy Comparison
Success Rates
- Urokinase has demonstrated significantly higher success rates:
Speed of Action
- Urokinase offers intermediate lysis rate but with better fibrinolytic specificity 3
- Streptokinase has been associated with the slowest rate of clot lysis in comparative studies 3
Safety Profile
Bleeding Risk
- Streptokinase is associated with:
Allergic Reactions
- Streptokinase has important safety concerns including allergic reactions 1
- Prior streptokinase exposure within 6 months is an absolute contraindication due to antibody formation 4
- Streptokinase antibodies can persist for years, reducing efficacy and increasing allergic reaction risk 4
Current Guideline Recommendations
The American College of Chest Physicians (ACCP) guidelines specifically recommend:
- "In patients undergoing intraarterial thrombolysis, we suggest rt-PA or urokinase over streptokinase (Grade 2C)" 1
The ACC/AHA guidelines note:
- "Streptokinase has been largely abandoned owing to lower efficacy and increased bleeding complications compared with urokinase" 1
Dosing Considerations
Urokinase
- Recommended dosage: 4,400 U/kg per hour for pulmonary embolism 1
- Cleared rapidly by the liver with elimination half-life of 12.6 ± 6.2 minutes 5
Streptokinase
- Recommended dosage: 250,000-U bolus given in 30 min, followed by 100,000 U/h infusion 1, 4
- Monitoring should include hemodynamic parameters every 2-3 hours during infusion 4
Special Populations
Pediatric Patients
- In pediatric patients, tissue plasminogen activator (tPA) is the agent of choice 1
- Decreased plasminogen levels in newborns reduce the thrombolytic effects of streptokinase and urokinase 1
- Complete resolution rates in children: streptokinase (53%), urokinase (43%), tPA (69%) 1
Patients with Previous Exposure
- Patients with known allergy to streptokinase or previous exposure should be given urokinase 1
- History of streptococcal pharyngitis within past 6 months is a contraindication for streptokinase 4
Cost Considerations
- Urokinase is significantly more expensive than streptokinase
- Average pharmacy cost for intra-arterial streptokinase: $165 vs urokinase: $1,142 (1986 data) 2
- Despite the cost difference, the increased efficacy and safety of urokinase make it the preferred agent 2
Clinical Decision Algorithm
First consideration: Patient's history of previous exposure to streptokinase or streptococcal infection
- If positive history → Use urokinase (absolute)
- If no history → Proceed to next step
Second consideration: Type of thromboembolic event
- For acute limb ischemia → Urokinase preferred
- For prosthetic valve thrombosis → Either agent (no significant difference in success rates) 1
Third consideration: Bleeding risk assessment
- High bleeding risk → Urokinase (more fibrin-specific)
- Lower bleeding risk → Either agent (with preference for urokinase)
Fourth consideration: Cost constraints
- Severe cost constraints → Streptokinase may be considered if no contraindications
- No significant cost constraints → Urokinase preferred
Common Pitfalls to Avoid
- Failing to check for previous streptokinase exposure or streptococcal infection
- Not monitoring coagulation parameters during streptokinase infusion
- Overlooking the need for appropriate anticoagulation after thrombolytic therapy
- Using streptokinase in patients with high bleeding risk due to its systemic effects
In conclusion, while both agents have been used historically for thrombolysis, the evidence strongly favors urokinase over streptokinase based on efficacy and safety considerations, despite its higher cost.