Structure and kinetics of CS585. Potency of CS585 and 12-HETrE. (A) Structure of CS585. (B) Synthesis of CS585 involved a 3-step synthesis starting with a pyrazine derivative. The pyrazine derivative reacted with an alcohol to form 4-((5-diphenylpyrazin-2-yl)(isopropyl)amino)butan-1-ol. This intermediate was converted to a second intermediate, 4-((5-diphenylpyrazin-2-yl)(amino)butyl 4-methanebenzenesulfonate. Finally, the prostacyclin receptor agonist CS585 (5-((4-((5,6-diphenylpyrazin-yl)(isopropyl)amino)butyl)thio)-2,4-dihydro-3H-,12,4-triazol-3-one) is formed. (C) PK were assessed in mouse plasma over a 24-hour period. (D) Aggregation dose-response comparison of washed human platelets treated with vehicle, CS585 (3.125-100 nM), or 12-HETrE (500-15 000 nM), stimulated with collagen (0.5 μg/mL) (n = 4). (E) Integrin αIIbβ3 activation, α-granule, and dense granule secretion dose-response comparison of washed human platelets treated with vehicle, CS585 (3.125-100 nM) or 12-HETrE (500-15 000 nM) stimulated with convulxin (25 ng/mL) (n = 4). Data represent mean ± SEM. A one-way analysis of variance (ANOVA) was performed using an uncorrected Fisher least significant difference post hoc test. Asterisks denote statistical differences between the vehicle and treated groups: ∗P < .05; ∗∗P < .01; ∗∗∗P < .001; ∗∗∗∗P < .0001. MFI, mean fluorescence intensity.