Switching from prasugrel to ticagrelor may cause transiently higher levels of platelet inhibition but can be done safely using a standard twice a day 90 mg ticagrelor dose, according to findings published March 21 in JACC: Cardiovascular Interventions. These findings will be presented at ACC.16 in Chicago.

Francesco Franchi, MD, and colleagues examined 82 patients who had undergone percutaneous coronary intervention for acute coronary syndrome and who were on maintenance dual antiplatelet therapy with aspirin 81 mg and prasugrel 10 mg for at least 14 days. Patients were randomized to either a maintenance dose of prasugrel 10 mg, a loading dose of ticagrelor 180 mg, followed by a maintenance dose of 90 mg twice a day, or maintenance dose ticagrelor 90 mg twice a day without a loading dose.

Results showed that at baseline, P2Y₁₂ reaction units (PRU) (p = 0.195), platelet reactivity index (PRI) (p = 0.283) and maximal platelet aggregation (MPA) (p = 0.444) were similar between all groups. After one week, PRU levels in the combined ticagrelor groups compared with prasugrel were within the 45 PRU noninferiority margin. Similar results were observed with PRI and MPA. There was a decrease in PRU, PRI and MPA levels as early as two hours after switching to ticagrelor, which lasted for up to 48 hours. There was also a significant reduction in platelet reactivity compared with prasugrel observed both with and without the use of a loading dose of ticagrelor (p < 0.001).

In addition, after switching to ticagrelor, there was an increase in platelet reactivity from 48 hours to one week. After one week, levels of PRU were nonsignificantly higher with prasugrel (p = 0.142), while the differences in PRI were statistically significant (p = 0.005) compared with the ticagrelor groups. Similar levels of platelet reactivity were shown with MPA (p = 0.568). There were no differences between the two ticagrelor groups at any time during the study.

These findings show that switching from prasugrel to ticagrelor was associated with a reduction in levels of platelet activity as early as two hours after switching and that there were no signs of drug interaction. There was also no increase in high on-treatment platelet reactivity rates, which were very low throughout the study.

“Overall, these results provide important pharmacodynamic insights to clinicians who may choose to switch patients from prasugrel to ticagrelor therapy, which can be performed without any concerns for drug interactions by simply transitioning to a standard 90 mg bid dosing regimen, without the need for a loading dose,” the authors write. 

Keywords: Acute Coronary Syndrome, Adenosine, Aspirin, Blood Platelets, Drug Interactions, Percutaneous Coronary Intervention, Platelet Activation, Platelet Aggregation, Platelet Aggregation Inhibitors, Platelet Function Tests, ACC Annual Scientific Session

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