L-371,257 is a compound used in scientific research which acts as a selective
antagonist
An antagonist is a character in a story who is presented as the main enemy or rival of the protagonist and is often depicted as a villain.oxytocin receptor with over 800x selectivity over the related vasopressin receptors. It was one of the first non-peptide oxytocin antagonists developed, and has good oral bioavailability, but poor penetration of the
blood–brain barrier
The blood–brain barrier (BBB) is a highly selective semipermeable membrane, semipermeable border of endothelium, endothelial cells that regulates the transfer of solutes and chemicals between the circulatory system and the central nervous system ...
, which gives it good peripheral selectivity with few central side effects. Potential applications are likely to be in the treatment of premature labour.