Eisai Co. Ltd. and Purdue Pharma LP, partners in the development and commercialization of a dual orexin receptor antagonist for insomnia, said the drug improved subjective measures of both sleep onset and maintenance at the end of the six-month, placebo-controlled treatment period of a large phase III study. The data were incorporated into the pair's December FDA new drug application for lemborexant, which Eisai said could potentially reduce the risk of nighttime falls.