L 366509

L 366509 is a spiroindenylpiperidine camphorsulfonamide oxytocin (OT) antagonist. Modifications led to a new series of o-tolylpiperazine (TP) camphorsulfonamides, exhibiting high affinity for OT receptors and selectivity over arginine vasopressin receptors. Notably, compound 7 (L-368,899) showed excellent OT receptor affinity, potency in inhibiting OT-stimulated uterine contractions, good aqueous solubility, and oral bioavailability in multiple species. Compound 7 has entered clinical testing as an oral and intravenous tocolytic agent. Molecular modeling suggests the TP camphorsulfonamide structure mimics the D-AA2-Ile3 dipeptide, crucial in potent OT antagonists[1].