What is "epelsiban"

Epelsiban (GSK-557,296-B) is an oral drug which acts as a selective, sub-nanomolar (Ki=0.13 nM) oxytocin receptor antagonist with >31000-fold selectivity over the related vasopressin receptors and is being developed by GlaxoSmithKline for the treatment of premature ejaculation in men. and as an agent to enhance embryo or blastocyst implantation in women undergoing embryo or blastocyst transfer associated with in vitro fertilization ( IVF).