A selective type III phosphodiesterase-3 (PDE3) inhibitor. Displays limited selectivity for PDE3A versus PDE3B (IC₅₀ = 27 and 50 nM). This inhibitory effect increases intracellular cAMP and inhibits platelet aggregation. Cilostamide also blocks PKB/Akt signaling pathway downstream via inhibition of Akt-activated PDE3B.