Eisai is having another go at getting its Alzheimer’s disease drug Aricept (donepezil), currently used to treat mild-to-moderate cases, approved in the USA for patients with more severe symptoms.

Eisai and partner Pfizer had their application turned down in October after the US Food and Drug Administration (FDA) said the file contained formatting deficiencies. They have now reformatted the dossier.

Aricept is the best-selling drug in its class, with sales recorded by Pfizer of $255 million dollars during the first nine months of this year, up 15%. But the drug, and others in the same class, have been attracting criticism of late by those who claim their modest benefits do not justify their price tag.

An approval in severe AD would help maintain Aricept’s sales momentum, and also make inroads in territory current held by Forest Laboratories’ Namenda (memantine), currently the only drug approved to treat severe AD in the USA. This product has been growing fast, with sales up 53% to $124 million in its fiscal second quarter ended September 30.

The severe AD submission was based on results from a six-month trial involving almost 250 nursing home patients with severe AD who experienced a significant improvement in both cognition and activities of daily living scores versus placebo..