Early studies with inhibitors of neprilysin such as candoxatril, ecadotril, or acetorphan resulted in augmentation of endogenous ANP availability,37 promoted diuresis, and reduced right atrial pressure and pulmonary capillary wedge pressure in subjects with HF.38, 39, 40, 41, 42, 43, 44 Larger studies had negative results and demonstrated harm. This evidence concerns the gene NPPA and hydrops fetalis.