Aspirin is an anti-platelet agent used to reduce the risk of thrombus formation in Acute Coronary Syndrome (ACS)
Mechanism of Action: Aspirin irreversibly inhibits cyclooxygenase (COX) enzymes, resulting in decreased synthesis of thromboxane A2, which plays a key role in platelet aggregation
Action
Dosage
Onset
Contraindications
Antiplatelet- COX2 Inhibition
162-325 mg/day
30 minutes
Hypersensitivity to aspirin, bleeding disorders, active bleeding, recent surgery, severe thrombocytopenia
AHA STEMI Guidelines- Aspirin Prior to PCI
Drug
Recommended Dosage
Indication
COR
LOE
Aspirin
162- to 325-mg load
Before procedure
I
B
81- to 325-mg daily
Maintenance dose (indefinite)
I
A
81 mg daily is preferred
Maintenance dose (indefinite)
IIa
B
2013 ACCF/AHA guideline. Circulation. 2013 Jan 29;127(4):e362-425.
Clopidogrel
Prasugrel
Mechanism of Action:
Irreversibly Inhibits ADP-induced platelet aggregation by blocking the binding of ADP to its receptor
Dosage:
60 mg orally once daily; 10 mg for patients of 75 years and older
Pharmacokinetics:
Rapidly absorbed with peak plasma concentrations within 1 hour of administration
Adverse Effects:
Bleeding, headache, nausea, diarrhea, dyspnea
Contraindications:
Active pathological bleeding, prior stroke, severe hepatic failure
Clinical Pearls:
Take with or without food; dose adjustment needed with strong CYP3A4 inhibitors
Practical Considerations:
Not recommended in patients ≥75 years of age
Prasugrel is contraindicated in patients with a history of stroke or transient ischemic attack (TIA), as it has been associated with an increased risk of bleeding in these patients.
Prasugrel should be discontinued at least 7 days prior to elective surgery or dental procedures to minimize the risk of bleeding.
Ticagrelor
Cangrelor
Mechanism of action:
Reversibly binds to P2Y12 receptor on platelets and inhibits the ADP-mediated platelet activation and aggregation
Dosage:
Loading dose: 30 mcg/kg IV bolus
Maintenance dose: 4 mcg/kg/min IV infusion
Duration of infusion: Until the end of the PCI procedure
PK:
Onset of action: Within 2 minutes of bolus administration
Elimination half-life: 3 to 6 minutes
Platelet function returns to baseline within 1 hour of discontinuation
Adverse Effects:
Dyspnea, hypotension, headache, bleeding
Clinical Pearls & Practical Considerations:
Discontinue 1 hour prior to CABG surgery to reduce bleeding risk
May be useful in patients who cannot tolerate oral P2Y12 inhibitors due to dysphagia or malabsorption
Antiplatelet Drug Chart
Drug
Prodrug?
Loading Dose
Maintenance Dose
Discontinue Prior to Surgery/Dental Procedures
Clopidogrel
Yes
300-600 mg
75 mg daily
5 days
Prasugrel
No
60 mg
10 mg daily
7-10 days
Ticagrelor
No
180 mg
90 mg twice daily
5 days
Cangrelor
No
30 mcg/kg/min for 4 minutes, then 4 mcg/kg/min
N/A (IV infusion only)
N/A
AHA STEMI Guidelines- P2Y12 Inhibitors Prior to PCI
Drug
Recommendation
LOE
COE
Clopidogrel
Loading dose 600mg early or at time of PCI
I
B
Maintenance dose: 75mg daily
I
B
Duration: Continue for 1 year (DES or BMS)
I
B
Continued beyond 1 y when DES placed
III
B
Prasugrel
Loading dose 60mg early or at time of PCI
I
B
Maintenance dose: 10mg daily
I
B
Duration: Continue for 1 year (DES or BMS)
I
B
Contraindicated (patients with STEMI and prior stroke or TIA)
III
B
Continued beyond 1 y when DES placed
III (harm)
B
Ticagrelor
Loading dose 180mg early or at time of PCI
I
B
Maintenance dose: 90mg twice daily
I
B
Duration: Continue for 1 year (DES or BMS)
I
B
ESC STEMI Guidelines: Antiplatelet Therapy
Recommendations
Class
Level
A potent P2Y12 inhibitor (prasugrel or ticagrelor), or clopidogrel if these are not available or are contraindicated, is recommended before (or at least at the time of) PCI and maintained over 12 months unless there are contraindications such as excessive risk of bleeding.
I
A
Aspirin (oral or IV, if unable to swallow) is recommended as soon as possible for all patients without contraindications.
I
B
Cangrelor may be considered in patients who have not received P2Y12 receptor inhibitors.
