Urokinase Administration Protocol for Acute Myocardial Infarction
For patients with acute myocardial infarction requiring urokinase thrombolytic therapy, administer urokinase as an intravenous bolus of 1 million units followed by a second bolus of 1 million units after 60 minutes, along with heparin (10,000 U bolus followed by 1,000 IU/hour for 48 hours). 1
Dosing Protocol
Initial Administration
- Give urokinase as an IV bolus of 1 million units
- Follow with a second bolus of 1 million units after 60 minutes
- Total dose: 2 million units
Concurrent Anticoagulation
- Administer heparin as a 10,000 U IV bolus
- Continue with heparin infusion at 1,000 IU/hour for 48 hours
- Adjust heparin to maintain aPTT at 1.5 to 2.0 times control (approximately 50-70 seconds) 2
Timing Considerations
- Administer urokinase within the first 6 hours of symptom onset for optimal efficacy 3
- Earlier administration (within 2 hours) is associated with better outcomes and improved wall motion at the infarct site 4
- Administration after 6 hours from symptom onset shows limited benefit in limiting necrotic focus or reducing mortality 3
Patient Selection
- Urokinase should be given to patients with nonselective fibrinolytic agents who are at high risk for systemic emboli, including:
- Large or anterior MI
- Atrial fibrillation
- Previous embolus
- Known LV thrombus 2
Monitoring During Administration
- Monitor for reperfusion signs within 60-180 minutes after initiation of therapy:
- Relief of symptoms
- Restoration of hemodynamic and electrical stability
- Reduction of at least 50% of initial ST-segment elevation on follow-up ECG 2
- Monitor daily platelet counts in patients receiving heparin 2
- Monitor fibrinogen levels (significant decrease expected with effective therapy) 5
Precautions and Contraindications
Exercise caution in patients with:
- Severe uncontrolled hypertension
- History of cerebrovascular events
- Recent trauma or major surgery
- Noncompressible vascular punctures
- Recent internal bleeding
- Pregnancy
- Active peptic ulcer 6
Absolute contraindications include:
- Previous hemorrhagic stroke
- Other strokes or cerebrovascular events within 1 year
- Known intracranial neoplasm
- Active internal bleeding
- Suspected aortic dissection 6
Expected Outcomes and Efficacy
- Reperfusion rates of approximately 60-70% can be expected 1, 7
- Peak serum creatine kinase levels are typically lower in patients achieving reperfusion 4
- Anterior infarction patients may show greater mortality benefit (10.3% vs 13.9% with heparin alone) 1
- Bleeding complications are relatively rare (approximately 0.4%) 1
Alternative Approaches
- For patients with hepatic impairment, consider dose reduction as urokinase is rapidly cleared by the liver with an elimination half-life of approximately 12.6 minutes 8
- Combined therapy with defibrinogenase may enhance thrombolytic efficacy and accelerate coronary thrombus lysis 7
Remember that primary PCI is preferred over thrombolysis when it can be performed in a timely fashion (within 120 minutes of first medical contact) by skilled operators in high-volume centers 6.