This is meant as a brief revision antiplatelet drug pharmacology. Antiplatelet agents have come up as a part of a question on oral anticogulation of AF (Question 4 from the first paper of 2015), alongside with novel oral anticoagulants.Similarly, Question 13.2 from the first paper of 2009 asked the candidates to "briefly outline the mode of action and half life of aspirin, tirofiban and clopidogrel". In order to simplify revision, the following table has been constructed.
|
Drug |
Chemical properties |
Mechanism |
Clearance |
Half-life |
Duration of effect |
|
Aspirin |
Salycilate; |
Irreversible COX-1 inhibition, thus decreased production of the prothrombotic thromboxane A2 |
Renal |
1-2 hrs |
7-10 days |
|
Clopidogrel |
Thienopyridine |
Irreversible inhibition of P2Y12 ADP receptor, thus inhibition of cAMP-dependent platelet activation |
50% renal, |
0.5-1 hrs |
7-10 days |
|
Prasugrel |
Thienopyridine |
Irreversible inhibition of P2Y12 ADP receptor, thus inhibition of cAMP-dependent platelet activation |
Renal |
7 hrs |
7-10 days |
|
Ticagrelor |
Nucleoside (adenosine) analogue |
Reversible inhibition of P2Y12 ADP receptor, thus inhibition of cAMP-dependent platelet activation |
Biliary |
7-8 hrs |
3-5 days |
|
Abciximab |
Fab fragment of a human monoclonal antibody |
Glycoprotein IIb/IIIa inhibition, thus inhibition of platelet binding to fibrinogen and von Willebrand factor. |
Reticulo-endothelial system |
0.5 hr |
18-24 hours |
|
Tirofiban |
Small molecule non-peptide |
Glycoprotein IIb/IIIa inhibition, thus inhibition of platelet binding to fibrinogen and von Willebrand factor. |
Renal |
2 hrs |
4-8 hours |
Siller‐Matula, Jolanta M., Julia Krumphuber, and Bernd Jilma. "Pharmacokinetic, pharmacodynamic and clinical profile of novel antiplatelet drugs targeting vascular diseases." British journal of pharmacology 159.3 (2010): 502-517.
Farid, Nagy A., Atsushi Kurihara, and Steven A. Wrighton. "Metabolism and disposition of the thienopyridine antiplatelet drugs ticlopidine, clopidogrel, and prasugrel in humans." The Journal of Clinical Pharmacology 50.2 (2010): 126-142.
Levine, Glenn N., et al. "Newer pharmacotherapy in patients undergoing percutaneous coronary interventions: a guide for pharmacists and other health care professionals." Pharmacotherapy: The Journal of Human Pharmacology and Drug Therapy 26.11 (2006): 1537-1556.