Streptokinase Cannot Be Repeated After 1 Hour
No, a second dose of streptokinase should never be given one hour after the first dose—or at any time after the initial administration—because neutralizing antibodies form rapidly (within 4 days) and persist for at least 10 years, rendering repeat doses ineffective and increasing the risk of severe allergic reactions. 1, 2, 3
Why Repeat Streptokinase Dosing Is Contraindicated
Antibody Formation and Loss of Efficacy
- Streptokinase is highly antigenic, and antistreptokinase antibodies rise to significant levels starting 4 days after the initial dose and can persist for at least 4–10 years in up to 50% of patients 1, 3
- These antibodies neutralize subsequent doses, making re-administration ineffective for achieving reperfusion 1, 3
- Prior streptokinase or anistreplase exposure is an absolute contraindication to further streptokinase use 2
Increased Risk of Allergic Reactions
- High antibody titers are associated with hypersensitivity reactions upon re-exposure 3
- Re-administration may lead to excessive bleeding complications beyond the already elevated baseline risk 1
What to Do If Reperfusion Fails at 1 Hour
Assessment of Reperfusion Status
- Monitor for indirect signs of reperfusion at 60–90 minutes after streptokinase initiation: relief of chest pain, hemodynamic/electrical stability, and ≥50% reduction in ST-segment elevation 1, 2
- If these criteria are not met, reperfusion has likely failed 1
Immediate Management Options
For failed fibrinolysis with ongoing ischemia:
Rescue PCI is the preferred strategy if the patient has a large infarct and can undergo angiography within 12 hours of symptom onset (Class IIa recommendation) 1
Immediate angiography is recommended for evidence of failed fibrinolysis or uncertainty about reperfusion success (Class IIa, Level B) 1
If rescue PCI is unavailable and reocclusion/reinfarction occurs, use a non-streptokinase fibrinolytic agent (alteplase, reteplase, or tenecteplase), as these do not cause antibody formation and can be safely re-administered 1, 2
Critical Timing Considerations
- The 3–24 hour window after successful fibrinolysis is optimal for angiography to avoid the early prothrombotic period while minimizing reocclusion risk 1
- For failed fibrinolysis, angiography should be performed immediately, not delayed 1
Common Pitfalls to Avoid
Do Not Wait Beyond 1 Hour to Decide on Rescue Therapy
- Reperfusion assessment should occur at 60–90 minutes, not earlier, as this is when indirect criteria become reliable 1, 2
- Delaying the decision to pursue rescue PCI or alternative fibrinolysis increases infarct size and mortality 1
Do Not Confuse Early Hypotension with Failed Reperfusion
- Streptokinase-induced hypotension occurs in approximately 44% of patients at a mean of 9 minutes after infusion starts, resolves spontaneously within 16 minutes, and does not indicate failed reperfusion 4
- This transient hypotension does not increase cardiogenic shock, mortality, or stroke risk 4
Do Not Use Streptokinase for Any Repeat Dosing Scenario
- Even in the late phase (48–50 hours), streptokinase re-administration is contraindicated due to antibody persistence 1, 3, 5
- One small case series reported successful repeat streptokinase dosing without immediate complications 5, but this contradicts all major guideline recommendations and the established immunologic evidence 1, 2, 3
Alternative Fibrinolytic Agents for Repeat Dosing
If mechanical revascularization is truly unavailable and reinfarction occurs:
- Alteplase (t-PA): 15 mg IV bolus, then 0.75 mg/kg over 30 min, then 0.5 mg/kg over 60 min (max 100 mg total) with IV heparin 1, 2
- Reteplase (r-PA): 10 U IV bolus × 2 doses given 30 minutes apart with IV heparin 1, 2
- Tenecteplase (TNK-tPA): Single weight-adjusted IV bolus (30–50 mg based on weight) with IV heparin 1, 2
These agents do not cause antibody formation and can be safely re-administered if needed 1, 2