All of the following are differences between clopidogrel and ticagrelor except?
d. The number of days to discontinue therapy prior to CABG. The recommended number of days prior to CABG surgery to stop clopidogrel or ticagrelor is 5. Patients in both the Ticagrelor versus Clopidogrel in Patients with Acute Coronary Syndromes (PLATO) trial and the Effects of Clopidogrel in Addition to Aspirin in Patients with Acute Coronary Syndromes without ST-Segment Elevation (CURE) trial had increased bleeding if the agents were not stopped at least 5 days prior to surgery. Although the competitive antagonist property of ticagrelor at the P2Y12 receptor and its short half-life (~7 hours) would lead clinicians to believe that ticagrelor could be stopped earlier than 5 days prior to surgery, that has not proven to be true.
Respiratory diseases should be closely monitored with the use of which of the following antiplatelet agents?
c. In the Ticagrelor versus Clopidogrel in Patients with Acute Coronary Syndromes (PLATO) trial, patients were more likely to experience dyspnea in the ticagrelor arm versus the clopidogrel arm (14% vs. 8 %). Also, more patients had to discontinue ticagrelor than clopidogrel because of dyspnea (0.9% vs. 0.1%). The mechanism for increased dyspnea is hypothesized to be triggered by adenosine. Ticagrelor inhibits the clearance of adenosine thereby increasing its concentration in the circulation. Although, more dyspnea results from ticagrelor use, there were no differences in forced expiratory volume in 1 second (FEV1) between ticagrelor and clopidogre.
Which of the following side effects differentiate ticlopidine from clopidogrel?
c. Neutropenia. Ticlopidine causes neutropenia in 2.4% of patients who are initiated on therapy. Nearly 1% of patients develop severe neutropenia. Therefore, a complete blood count is required every 2 weeks during initiation of therapy for the first 3 months of therapy. Both agents can cause diarrhea and rash. Structurally, these two drugs are so similar that allergic cross-reactivity is expected. Thrombotic thrombocytopenic purpura has been reported with both agents. There have been >100 cases of thrombotic thrombocytopenic purpura reported with the use of ticlopidine and clopidogrel.
By which of the following mechanisms do clopidogrel and ticlopidine exert their antiplatelet effects?
c. Adenosine diphosphate (ADP) inhibitor. ADP is released from red blood cells, activated platelets, and damaged endothelial cells, leading to platelet adhesion and aggregation. However, the precise mechanism of its action has not been completely identified. ADP blockade decreases the expression of the glycoprotein IIb/IIIa receptor. Platelet inhibition occurs at maximal effect within 3 to 5 days and produces approximately 40% to 50% platelet inhibition. The onset and degree of platelet inhibition can be expedited with use of loading doses (300 to 600 mg).
Which of the following glycoprotein IIb/IIIa inhibitors has the highest incidence of severe thrombocytopenia?
b. Abciximab. All glycoprotein IIb/IIIa inhibitors may cause thrombocytopenia. However, abciximab has the highest rate of all, based on the clinical trials.
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