The acetylcholinesterase inhibitor phenserine, the (-)-enantiomer of a phenylcarbamate derivative of physostigmine, is being developed as a potential therapy for Alzheimer's disease by Axonyx, under license from the National Institutes of Health/National Institute on Aging. In March 2005, Axonyx suspended patient recruitment for the ongoing phase III trials of phenserine, after the drug failed to meet the primary endpoints of the first of these trials, but in May 2005, the company was planning to reformulate the drug.