Switching From Cangrelor to Prasugrel in Patients Undergoing Percutaneous Coronary Intervention: The Switching Antiplatelet-6 (SWAP-6) Study.

Background: A drug-drug interaction (DDI) may occur when transitioning from intravenous P2Y inhibition with cangrelor to oral P2Y inhibition with prasugrel. However, this has never been tested in patients undergoing percutaneous coronary intervention (PCI).

Objectives: This study sought to rule out a DDI when cangrelor and prasugrel are concomitantly administered in PCI patients.

Methods: SWAP-6 (Switching Antiplatelet-6) was a prospective, randomized, 3-arm, open-label pharmacokinetic (PK) and pharmacodynamic (PD) study. Patients (N = 77) were randomized to 1) prasugrel only at the start of PCI, 2) cangrelor plus prasugrel concomitantly at the start of PCI, or 3) cangrelor at the start of PCI plus prasugrel at the end of infusion. Cangrelor infusion was maintained for 2 hours. PK/PD assessments were performed at baseline and 6 time points postrandomization. The primary endpoint was noninferiority in VerifyNow (Werfen) P2Y reaction units measured at 4 hours after randomization between cangrelor plus prasugrel concomitantly administered vs prasugrel only. PK assessments included plasma levels of the active metabolite of prasugrel.

Results: Compared with prasugrel, cangrelor further enhances P2Y inhibitory effects. At 4 hours postrandomization, P2Y reaction unit levels were significantly lower with prasugrel only compared to cangrelor and prasugrel concomitantly administered (least squares means difference = 130; 95% CI: 85-176), failing to meet the prespecified noninferiority margin. Findings were corroborated by multiple PD assays. The active metabolite of prasugrel levels were not affected by concomitant administration of cangrelor and were low at the end of cangrelor infusion.

Conclusions: In patients undergoing PCI, concomitant administration of prasugrel with cangrelor leads to a marked increase in platelet reactivity after stopping cangrelor infusion, supporting the presence of a DDI. (Switching Antiplatelet Therapy-6 [SWAP-6]; NCT04668144).