title: Earlier recovery of platelet function after discontinuation of treatment with ticagrelor compared with clopidogrel in patients with high antiplatelet responses.
abstract: BACKGROUND
  The rate of recovery of platelet function after discontinuation of P2Y(12) inhibitors depends on the reversibility of the antiplatelet effect and the extent of the on-treatment response. P2Y(12) inhibition increases the bleeding risk in patients requiring surgery.
  
  
  OBJECTIVE
  To evaluate recovery of platelet function after discontinuation of ticagrelor vs. clopidogrel in stable coronary artery disease (CAD) patients with high levels of platelet inhibition (HPI) during the ONSET/OFFSET study.
  
  
  METHODS
  Patients received aspirin 75-100 mg per day and either ticagrelor 90 mg twice-daily or clopidogrel 75 mg daily for 6 weeks. This subanalysis included patients with HPI after the last dose of maintenance therapy, defined as: inhibition of platelet aggregation (IPA) > 75% 4 h post-dose (ADP 20 μm, final extent); < 120 P2Y(12) reaction units 8 h post-dose (VerifyNow P2Y(12) assay); or platelet reactivity index < 50% 8 h post-dose (VASP-P assay).
  
  
  RESULTS
  IPA > 75% was observed in 39 out of 47 ticagrelor-treated and 17 out of 44 clopidogrel-treated patients. The rate of offset of IPA over 4-72 h was greater with ticagrelor (IPA %/hour slope: -1.11 vs. -0.67 for clopidogrel; P < 0.0001). Mean IPA was significantly lower with ticagrelor than clopidogrel between 48 and 168 h post-dose (P < 0.01). Similar findings were observed with the other assays. The average time for IPA to decline from 30% to 10% was 50.8 h with ticagrelor vs. 110.4 h with clopidogrel.
  
  
  CONCLUSIONS
  In patients with HPI, recovery of platelet function was more rapid after discontinuation of ticagrelor than clopidogrel leading to significantly greater platelet reactivity by 48 h after the last dose in the ticagrelor group.
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit and Department of Cardiovascular Science, University of Sheffield, Sheffield, UK. r.f.storey@sheffield.ac.uk
authors.forename: R F
authors.initials: RF
authors.lastname: Storey
authors.forename: K P
authors.initials: KP
authors.lastname: Bliden
authors.forename: R
authors.initials: R
authors.lastname: Ecob
authors.forename: A
authors.initials: A
authors.lastname: Karunakaran
authors.forename: K
authors.initials: K
authors.lastname: Butler
authors.forename: C
authors.initials: C
authors.lastname: Wei
authors.forename: U
authors.initials: U
authors.lastname: Tantry
authors.forename: P A
authors.initials: PA
authors.lastname: Gurbel
mesh_terms: D000241:Adenosine / Q000008:administration & dosage / Q000031:analogs & derivatives*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001792:Blood Platelets / Q000187:drug effects* / Q000502:physiology*; D000077144:Clopidogrel; D003324:Coronary Artery Disease / Q000097:blood* / Q000188:drug therapy*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage*; D010979:Platelet Function Tests; D058921:Purinergic P2Y Receptor Antagonists / Q000008:administration & dosage*; D000077486:Ticagrelor; D013988:Ticlopidine / Q000008:administration & dosage / Q000031:analogs & derivatives*; D013997:Time Factors
chemical_list: D010975:Platelet Aggregation Inhibitors; D058921:Purinergic P2Y Receptor Antagonists; D000077144:Clopidogrel; D000077486:Ticagrelor; D000241:Adenosine; D013988:Ticlopidine