Cardiology>>>>>Ischaemic heart disease
Question 15#

Which one of the following statements regarding the new generation of antiplatelet drugs is not true?

A. Clopidogrel, prasugrel, and ticagrelor all inhibit the same receptor (P2Y12 ADP receptor)
B. Clopidogrel and prasugrel are irreversible inhibitors, whereas ticagrelor is reversible
C. Clopidogrel and prasugrel are both prodrugs which are metabolized to the active form, whereas ticagrelor acts directly
D. Ticagrelor requires twice daily maintenance, whereas clopidogrel and prasugrel are once daily
E. All are converted to the active metabolite by the hepatic cytochrome enzyme (CYP3A4) pathway

Correct Answer is E

Comment:

Clopidogrel and prasugrel are both pro-drugs, irreversible inhibitors, and once-daily regimes. The maintenance dose of prasugrel is halved for weight <60 kg or age >75 years. Clopidogrel is converted to its active metabolite by the cytochrome enzyme pathway; this accounts for the variability of action in some patients (hyporesponders) which can lead to stent thrombosis. Prasugrel is converted to its active form faster and more consistently. Ticagrelor is reversible and direct acting and therefore is again faster acting and more predictable than copidogrel. All inhibit the P2Y12 ADP platelet receptor.