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Several molecules, including thrombin, ADP, and thromboxane A2, activate platelets by acting on cell surface receptors. Interference with post receptor signaling can alter platelet functions. Agents that increase platelet cyclic AMP decrease platelet aggregation by preventing platelet shape change and granule release.
Dipyridamole and cilostazol work by decreasing the activity of platelet phosphodiesterase, the enzyme responsible for breakdown of cyclic AMP. Cilostazol, in addition to inhibition of platelet aggregation, also is a direct arterial vasodilator. Cilostazol is approved by the FDA for the treatment of intermittent claudication (peripheral arterial disease).