Ecraprost [AS 013, Circulase] is a prodrug of prostaglandin E(1) within lipid microspheres that is being developed in Japan by Mitsubishi Pharma Corporation and Asahi Glass. It was originally in development with Welfide Corporation. On 1 October 2001, Welfide Corporation (formerly Yoshitomi) merged with Mitsubishi-Tokyo Pharmaceuticals to form Mitsubishi Pharma Corporation. The new company is a subsidiary of Mitsubishi Chemical. Taisho and Seikagaku Corporation had been involved in the development of ecraprost but discontinued their licences to do so. The effects of ecraprost on reperfusion injury, in preclinical studies, had been reported by Taisho. Ecraprost is in phase II in Japan and was in phase II in Europe for the treatment of peripheral arterial disease. It was also in a phase II study in the treatment of diabetic neuropathies. However, this is no longer an active indication. A phase III trial using a lipid emulsion of ecraprost [Circulase] is underway with Mitsubishi Pharma Corporation in the US, using ecraprost for the treatment of patients with severe peripheral arterial disease, which, because of decreased blood flow to the extremities, can lead to painful ulcers on the legs and feet and subsequent amputation. Alpha Therapeutic Corporation (a former subsidiary of Mitsubishi Pharma) was initially involved in trials of ecraprost in the US, but this responsibility has been taken over by the parent company.