Sampatrilat is a dual inhibitor of neutral endopeptidase (NEP) and angiotensin converting enzyme (ACE), which is under development by Pfizer and Shire (previously Roberts Pharmaceutical) for the potential treatment of hypertension. As of 1995, Pfizer had taken the compound into phase II clinical trials [179233]. In April 1997, Roberts Pharmaceutical, through its wholly owned subsidiary Roberts Laboratories Inc, received an exclusive license from Pfizer to develop and market sampatrilat for the treatment of essential hypertension and congestive heart failure. The agreement provided for transfer of data and the awarding of patent rights to Roberts [240809]. Although in June 2000, Shire confirmed it had discontinued all development of this drug [372652], by December 2000 it had recommenced studies with a reformulation of sampatrilat that achieved a 4-fold increase in oral bioavailability. A clinical trial with the new formulation was to be initiated in 2001, with results expected during the second quarter of 2001. The company also revealed that it was seeking a licensing partner at this time [394238]. In November 2001, Shire confirmed that while the project was undergoing further development with a view to outlicensing, it was unlikely to take this project into phase II alone [429562].