Ticagrelor and prasugrel are newer antiplatelet drugs which, like clopidogrel, block the P2Y12 platelet receptor to inhibit platelet aggregation. Compared with clopidogrel, both ticagrelor and prasugrel have greater clinical efficacy but also have a higher risk of bleeding and are much more costly. Therefore, some institutions and providers switch patients from ticagrelor or prasugrel to clopidogrel in an effort to lower bleeding risk, stem costs, or otherwise ensure that patients can safely adhere to long-term P2Y12 inhibitor therapy. From a pharmacodynamic perspective, switching patients from ticagrelor or prasugrel to clopidogrel comes at a cost of less antiplatelet efficacy. However, it is unclear if antiplatelet efficacy is diminished enough to affect clinical outcomes. This is because clinical trial data investigating such a switch is scant, leaving the clinician unsure as to the acceptability of this practice. Current clinical trial data have thus far not shown any clinical detriment from switching from ticagrelor or prasugrel to clopidogrel, but there are many limitations to these investigations. So although a large-scale switch of patients from ticagrelor or prasugrel to clopidogrel is not recommended, if the patient is unable to adhere to long-term ticagrelor or prasugrel therapy, switching him/her to clopidogrel seems to be a reasonable practice to maintain chronic suppression of platelet aggregation and minimize the risk of ischemic events.

中文翻译：

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从替卡格雷或普拉格雷改用氯吡格雷。

替卡格雷和普拉格雷是较新的抗血小板药物，与氯吡格雷一样，可阻断P2Y12血小板受体以抑制血小板聚集。与氯吡格雷相比，替卡格雷和普拉格雷均具有更高的临床疗效，但出血风险更高，且成本更高。因此，一些机构和医疗服务提供者将患者从替卡格雷或普拉格雷改用氯吡格雷，以降低出血风险，降低治疗成本或确保患者可以安全地接受长期P2Y12抑制剂治疗。从药效学的角度来看，将患者从替卡格雷或普拉格雷改用氯吡格雷的代价是抗血小板药效降低。但是，尚不清楚抗血小板药效是否降低到足以影响临床结果的程度。这是因为调查这种转换的临床试验数据很少，使临床医生不确定这种做法的可接受性。迄今为止，目前的临床试验数据尚未显示出从替卡格雷或普拉格雷改用氯吡格雷的任何临床危害，但这些研究存在许多局限性。因此，尽管不建议将患者从替卡格雷或普拉格雷改用氯吡格雷，但如果患者不能长期接受替卡格雷或普拉格雷的长期治疗，将他/她改用氯吡格雷似乎是维持慢性的合理方法。抑制血小板凝集并使缺血事件的风险降至最低。但是这些调查有很多限制。因此，尽管不建议将患者从替卡格雷或普拉格雷改成氯吡格雷，但如果患者不能长期接受替卡格雷或普拉格雷的长期治疗，将他/她改用氯吡格雷似乎是维持慢性的合理做法。抑制血小板凝集并使缺血事件的风险降至最低。但是这些调查有很多限制。因此，尽管不建议将患者从替卡格雷或普拉格雷改成氯吡格雷，但如果患者不能长期接受替卡格雷或普拉格雷的长期治疗，将他/她改用氯吡格雷似乎是维持慢性的合理做法。抑制血小板凝集并使缺血事件的风险降至最低。