Sequence of Medication Administration in Acute Myocardial Infarction
In acute myocardial infarction (MI), aspirin should be administered first, followed by clopidogrel, then anticoagulation with enoxaparin, followed by tenecteplase, and finally atorvastatin. This sequence optimizes outcomes by prioritizing immediate antithrombotic therapy before fibrinolysis.
Initial Management: Aspirin and Clopidogrel
- Aspirin should be given as soon as possible after STEMI diagnosis is deemed probable, at a dose of 150-325 mg in a chewable form (non-enteric coated) or 250-500 mg IV if oral administration is not possible 1
- Clopidogrel should be administered immediately after aspirin, with a loading dose of 300 mg (75 mg if age >75 years) 1
- This dual antiplatelet therapy is crucial to prevent platelet aggregation and reduce the risk of reinfarction and mortality 1
Anticoagulation: Enoxaparin
- Enoxaparin should be administered after the antiplatelet agents but before fibrinolytic therapy 1
- The recommended dosing is an IV bolus of 30 mg followed by 1 mg/kg subcutaneously every 12 hours (with dose adjustment for patients >75 years old) 1, 2
- Enoxaparin is preferred over unfractionated heparin as it has shown better efficacy in reducing ischemic complications 3, 4
Fibrinolytic Therapy: Tenecteplase
- Tenecteplase should be administered after antiplatelet and anticoagulant therapy has been initiated 1, 5
- It is given as a single weight-adjusted IV bolus (30-50 mg based on weight) 5
- For patients ≥75 years old, a 50% dose reduction is recommended to reduce bleeding risk 5
- Tenecteplase is preferred as it is a fibrin-specific agent with convenient single-bolus administration 1
Statin Therapy: Atorvastatin
- Atorvastatin should be administered after the acute reperfusion therapies have been given 1
- High-intensity statin therapy should be initiated as early as possible during the acute phase, but after the more time-sensitive reperfusion therapies 1
Important Considerations
- The entire sequence should be initiated as rapidly as possible, with minimal delay between medications 1
- If primary PCI is available within 120 minutes of STEMI diagnosis, it is the preferred reperfusion strategy over fibrinolysis 1, 5
- Continuous ECG monitoring with defibrillator capacity should be initiated immediately in all patients with suspected STEMI 5
- After fibrinolysis, patients should be transferred to a PCI-capable center immediately 1
Common Pitfalls to Avoid
- Delaying aspirin administration - it should be the first medication given 1
- Using enteric-coated aspirin, which has slower onset of action 1
- Using fondaparinux as the sole anticoagulant for PCI (contraindicated) 1
- Administering tenecteplase before adequate antiplatelet and anticoagulant coverage 1, 5
- Failing to adjust doses for elderly patients (>75 years), especially for clopidogrel and tenecteplase 1, 5
This sequence prioritizes rapid restoration of coronary blood flow while minimizing the risk of bleeding complications, optimizing outcomes in terms of mortality and morbidity in acute MI patients.