Vintoperol (also known as RGH 2981), a peripheral circulation-enhancing compound that was developed as a moderate serotonin and calcium channel antagonist. Vintoperol was studied for the treatment of arterial occlusive disease and peripheral vascular disorders. It was shown that this compound interfered with platelet aggregation both in vitro and in vivo and possessed potent antithrombotic effects in thrombosis models in which platelet activation was mainly involved. Vintoperol participated in phase II clinical trials in Japan for the treatment patients with arterial occlusive disorders, peripheral vascular disorders, and thrombosis. However, because of its toxic side effects, vintoperol was discontinued from the clinical practice.