ACT-246475 is a selective and reversible P2Y receptor antagonist inducing inhibition of platelet aggregation (IPA). A randomized, double-blind, placebo-controlled, parallel-design study was performed to investigate the safety, tolerability, pharmacokinetics, and pharmacodynamics of escalating single subcutaneous doses of ACT-246475 (1, 2, 4, 8, 16, or 32 mg) in healthy male subjects (N = 8 per dose, 3:1 active:placebo ratio). Pharmacodynamic effects were assessed based on maximum platelet aggregation and P2Y reaction units using light transmission aggregometry and VerifyNow assays, respectively. ACT-246475 was safe and well tolerated up to 32 mg based on adverse event data and absence of clinically relevant changes in hematology, biochemistry, vital signs, and electrocardiogram variables. Median time to reach maximum plasma concentration was 0.5-0.75 hours, and geometric mean terminal half-life ranged from 1.3 to 9.2 hours across the tested dose range. Exposure to ACT-246475 was dose proportional across all dose groups. The maximal %IPA was reached within 30 minutes after subcutaneous administration of ACT-246475. A dose-dependent duration and extent of effect were observed based on area under the effect curve and maximum effect data. Similar results were observed for maximum platelet aggregation and P2Y reaction units. The %IPA was ≥85% at doses ≥2 mg. This level of %IPA was extended to at least 12 hours in the 32-mg dose group. The safety and pharmacokinetic/pharmacokinetic profile with quick onset and adequate duration of IPA support further investigation in patients with coronary artery disease.

Reduced pharmacodynamic (PD) effects of irreversible oral P2Y12 receptor antagonists have been reported when administered during cangrelor infusion. Therefore, the PD interaction liability of the novel P2Y12 receptor antagonist selatogrel with irreversible (i.e., clopidogrel, prasugrel) and reversible (i.e., ticagrelor) oral P2Y12 receptor antagonists was investigated in vitro and in healthy subjects. In vitro, selatogrel reduced the effects of clopidogrel and prasugrel in a concentration-dependent manner, while additive effects were observed for the combination of selatogrel and ticagrelor. Accordingly, a single-center, randomized, double-blind, two-way crossover study was conducted consisting of six groups. In each group (N = 12), an open-label loading dose of 300 or 600 mg clopidogrel, 60 mg prasugrel, or 180 mg ticagrelor was administered 30 minutes (i.e., at t max of selatogrel) or 12 hours after a single subcutaneous dose of 16 mg selatogrel or placebo. Inhibition of platelet aggregation (IPA) was assessed at various time points up to 48 hours. Reduced IPA was determined when clopidogrel or prasugrel was administered 30 minutes after selatogrel (∼40 and 70% lower IPA, respectively, at 24 hours postdosing). However, when administering prasugrel 12 hours after selatogrel, IPA was not impacted (>90% IPA) and in the case of clopidogrel reduced effects were partially mitigated. Similar IPA was determined for ticagrelor when administered 30 minutes after selatogrel or placebo. In conclusion, reduced IPA was observed for clopidogrel and prasugrel when administered after selatogrel, which can be mitigated by applying an appropriate time interval. No PD interaction with ticagrelor was observed.