With generic competition poised to cut deep into revenue from its top product, the preterm birth drug Makena (hydroxyprogesterone caproate), Amag Pharmaceuticals Inc. has moved to acquire a midstage preeclampsia drug from Velo Bio LLC. If successful, it could transform the old digoxin poisoning treatment into an essential maternal care product for an indication with no FDA-approved therapy, a scenario that CEO Bill Heiden called "a potential $1 billion project opportunity."