Clopidogrel Platelet Function Tests
Caveats and Controversies
Not all patients with CYP2C19 polymorphisms are resistant to clopidogrel. Of 6 patients with one polymorphism at our institution, only 2 were resistant by VerifyNow testing. In one study, even some patients with 2 polymorphisms were not resistant by VASP testing. Studies have shown that patients with diabetes, high BMI or age over 70 years with a CYP2C19 polymorphism have poorer metabolism of clopidogrel than expected from the CYP2C19 polymorphism alone. We have already mentioned the platelet ADP receptor polymorphism, the duodenal absorption polymorphism and the PON1 enzyme activity and these in combination with a CYP2C19 polymorphism, may decrease clopidogrel metabolism more profoundly.
Polymorphism May Require Another Factor
Jump to section:
- Learning Objectives
- Platelet Function Tests for the Detection of Clopidogrel Resistance1
- Platelet Function Tests for the Detection of Clopidogrel Resistance
- Caveat: There Is No Perfect Platelet Function Test...
- Problems With Testing For Clopidogrel
- How We Choose a Testing Method
- Methodology Table
- Platelet Function Testing Available at Mayo Clinic Florida
- Light Transmission Platelet Aggregometry Studies (LTA)
- Platelet Aggregation (Cont'd)
- Normal Patient
- Accumetrics VerifyNow Test
- VerifyNow P2Y12 Test
- P2Y12 Test Interferences
- P2Y12 Antagonists2
- Can These Platelet Function Tests Be Used for Ticagrelor (Brilinta/Brilique)?
- PFA–100 (Cont'd)
- INNOVANCE PFA P2Y
- TEG — Platelet Mapping
- Results of VerifyNow Testing
- 2009–2011 Clopidogrel Response at 30%
- Genetic Testing: Clopidogrel Metabolism
- Clopidogrel Metabolism
- Number of Gene Polymorphisms
- Clopidogrel Metabolism and Genetic Polymorphisms
- Why Do Genetic Testing?
- Clopidogrel Genetics (Cont'd)
- Caveats — Other Reasons for Poor Response to Clopidogrel
- CYP2C19 Polymorphism May Require Another Factor
- Controversy for Clopidogrel
- Warning: Diminished Effectiveness In Poor Metabolizers
- What Does Warning Mean For Clinicians With Patients On Clopidogrel?
- FDA Answer
- More Questions