Prinaberel (INN, USAN) (developmental code names ERB-041, WAY-202041) is a synthetic, nonsteroidal, and highly selective agonist of the ERò subtype of the estrogen receptor. It is used in scientific research to elucidate the role of the ERò receptor. Studies have indicated that selective ERò agonists like prinaberel could be useful in the clinical treatment of a variety of medical conditions including inflammatory bowel disease, rheumatoid arthritis, endometriosis, and sepsis. Accordingly, prinaberel either was or still is under investigation by Wyeth for the treatment of some of these conditions.