Eisai is buying out Purdue Pharma’s rights to the worldwide collaboration for the development and commercialization of lemborexant, an investigational sleep-wake regulation agent being studied for the treatment of multiple sleep-wake disorders, including insomnia and irregular sleep-wake rhythm disorder (ISWRD) in patients with Alzheimer’s Disease. Under the terms of the original agreement established in 2015, Eisai and Purdue shared the costs of lemborexant global clinical studie...