Recent evidence demonstrates that intravenous morphine significantly reduces absorption and delays onset of action of oral P2Y12 receptor inhibitors in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (pPCI). We aimed to assess the influence of intravenous fentanyl compared with morphine on pharmacokinetics and pharmacodynamics of ticagrelor and its active metabolite (AR-C124910XX) in patients undergoing pPCI for STEMI.