Ticagrelor is a reversible P2Y12 receptor inhibitor whereas clopidogrel and prasugrel are irreversible inhibitors.
Ticagrelor does not require metabolic activation, absorption is rapid and half life is between 7-12 hours; while clopidogrel and prasugrel requires metabolic activation
P2Y12 receptor inhibition by ticagrelor is more rapid and achieves a markedly higher degree of inhibition of adenosine diphosphate (ADP) mediated platelet aggregation. This is possibly a reason for higher degree of bleeding with ticagrelor than clopidogrel.
Lower rates of fatal bleeds with ticagrelor compared to prasugrel is thought to be due to the reversible nature of inhibition with ticagrelor compared to the irreversible P2Y12 receptor inhibition by prasugrel.
Arora S, Shemisa K, Vaduganathan M, Qamar A, Gupta A, Garg SK, Kumbhani DJ, Mayo M, Khalili H, Pandey A, Das SR. Premature Ticagrelor Discontinuation in Secondary Prevention of Atherosclerotic CVD. J Am Coll Cardiol. 2019;73(19): 2454-64.