Abstract

Early structure-activity studies on racemic tryptophan ester and amide NK-1 antagonists 5-7 led to the discovery that the potency of the series could be markedly increased by moving the carbonyl function in these molecules to an off-chain position as in the 3-aryl-1,2-diacetamidopropane 9. Further medicinal chemistry incorporating this change resulted in the discovery of a novel series of highly potent aryl amino acid derived NK-1 antagonists of the R stereoisomeric series (IC50's = 100 pM to > 5 microM). Compounds in this series were shown to be competitive antagonists using an in vitro NK-1 smooth muscle assay, and this data correlated well with observed human NK-1 binding affinities. Two of these agents, (R)-25 and (R)-32, blocked intrathecal NK-1 agonist-driven [Ac-[Arg6,Sar9,Met(O2)11]- substance P 6-11 (Ac-Sar9)] nociceptive behavior in mice. Both compounds potently blocked the neurogenic dural inflammation following trigeminal ganglion stimulation in the guinea pig after intravenous administration. Further, upon oral administration in this model, (R)-32 was observed to be very potent (ID50 = 91 ng/kg) and have a long duration of action (> 8 h at 1 micrograms/kg). Compound (R)-32, designated LY303870, is currently under clinical development as an NK-1 antagonist with a long duration of action.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.