Eisai Co. Ltd. and Imbrium Therapeutics LP said the U.S. Food and Drug Administration accepted the companies' application seeking approval for lemborexant for treating insomnia.

Insomnia is the most common sleep disorder, affecting 30% of the adult population globally. Lemborexant works by acting the orexin neurotransmitter system, which regulates a person's wakefulness.

The new drug application is based on the results of two phase 3 trials called Sunrise 1 and Sunrise 2, which enrolled about 2,000 patients.

The U.S. FDA is expected to decide lemborexant's approval by Dec. 27.

Imbrium is a unit of Stamford, Conn.-based Purdue Pharma LP. Tokyo's Eisai and Purdue Pharma are jointly developing lemborexant for sleep-wake disorders.

Lemborexant is being evaluated in a phase 2 study in patients with irregular sleep-wake rhythm disorder and mild to moderate Alzheimer's dementia.

Meanwhile, Eisai is also seeking Japanese approval for lemborexant as an insomnia therapy.