title: Platelet adenosine diphosphate receptor antagonists: ticlopidine to ticagrelor-a long continuing journey.
abstract: Platelet aggregation plays a central role in the pathogenesis of atherothrombosis. Platelet adenosine diphosphate (ADP) receptor antagonists (ticlopidine, clopidogrel, prasugrel, and ticagrelor) are a major advance in the treatment of atherothrombotic diseases, especially acute coronary syndromes (ACS). Ticlopidine was the first thienopyridine introduced into clinical practice, but its potentially serious haematological side-effects limited its use and it was quickly eclipsed by clopidogrel. Clinical trials established aspirin plus clopidogrel as the standard dual anti-platelet therapy in patients with ACS and patients undergoing percutaneous coronary intervention (PCI) with stenting. Clopidogrel was found to have pharmacokinetic and pharmacodynamic limitations. Prasugrel is the next approved thienopyridine that has shown superior efficacy in ACS patients undergoing PCI in comparison to clopidogrel, although at the cost of a higher bleeding risk. Ticagrelor is the latest non-thienopyridine ADP receptor blocker that is potent, effective, reversible, and relatively safer as compared to clopidogrel. Both prasugrel and ticagrelor are more potent than clopidogrel. The data so far suggests that ticagrelor has a wider applicability in usage in patients with ACS as compared to prasugrel. Prasugrel however seems to be better tolerated. Search is on for newer more potent but safer anti-platelet agents.
authors.affiliation: Fortis Flt Lt Rajan Dhall Hospital, Vasant Kunj, New Delhi, India. kaul.upendra@gmail.com
authors.forename: Upendra
authors.initials: U
authors.lastname: Kaul
authors.forename: Aijaz H
authors.initials: AH
authors.lastname: Mansoor
mesh_terms: D000241:Adenosine / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000627:therapeutic use; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D006470:Hemorrhage / Q000139:chemically induced; D006801:Humans; D062645:Percutaneous Coronary Intervention / Q000009:adverse effects*; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use*; D017410:Practice Guidelines as Topic; D058921:Purinergic P2Y Receptor Antagonists / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use*; D012307:Risk Factors; D013927:Thrombosis / Q000097:blood / Q000209:etiology / Q000517:prevention & control*; D000077486:Ticagrelor; D013988:Ticlopidine / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: D010975:Platelet Aggregation Inhibitors; D058921:Purinergic P2Y Receptor Antagonists; D000077486:Ticagrelor; D000241:Adenosine; D013988:Ticlopidine