The effect of 2-(3-benzoylphenyl)propionic acid [22071-15-4], S 1429 (I) [76823-82-0], and 1-(p-chlorobenzhydryl)-4-[2-(2-hydroxyethoxy)ethyl]piperazine [68-88-2] on prostaglandin synthesis, blood coagulation, platelet aggregation, lysosomal enzyme release, and binding to serum albumin was studied.Studies were performed on rats, rabbits, and human healthy volunteers.The inhibition of prostaglandin synthesis was less with S 1429 than with 2-(3-benzoylphenyl)propionic acid; 1-(p-chlorobenzhydryl)-4-[2-(2-hydroxyethoxy)ethyl]piperazine exerted a weak inhibition.Bleeding time was moderately prolonged at the third and eighth hour when 2-(3-benzoylphenyl)propionic acid was used and at the third hour when S 1429 was used.After treatment with 1-(p-chlorobenzhydryl)-4-[2-(2-hydroxyethoxy)ethyl]piperazine, no significant variations were observed2-(3-Benzoylphenyl)propionic acid and S 1429 significantly decreased ADP-dependent platelet aggregation, while 1-(p-chlorobenzhydryl)-4-[2-(2-hydroxyethoxy)ethyl]piperazine had no effect.2-(3-Benzoylphenyl)propionic acid and S 1429 produced only a weak, non-significant stabilization of the membrane of rat liver lysosomes.One hundred μM 2-(3-benzoylphenyl)propionic acid bound almost completely to albumin, while S 1429 and 1-(p-chlorobenzhydryl)-4-[2-(2-hydroxyethoxy)ethyl]piperazine showed a lower affinity.