 However, following the issuing of a non-approvable letter for the modified-release 15 mg formulation and an approvable letter with stipulations for the 5 mg and 10 mg immediate-release version by the FDA in May 2006, Pfizer ended its relationship with Neurocrine.Neurocrine's stock price dropped 60% on the news.Following a resubmission, the FDA in December 2007 deemed Neurocrine's new drug application (NDA) 'approvable' in the 5 and 10 mg formulations, but requested new studies as a prerequisite to approval, including a clinical trial in the elderly, a safety study comparing adverse effects to those of similarly marketed drugs, and a preclinical study examining indiplon's safety in the third trimester of pregnancy.