The structure–activity relationship of a series of tricyclic-sulfonamide compounds 11–32 culminating in the discovery of N-[trans-4-(4, 5-dihydro-3, 6-dithia-1-aza-benzo [e] azulen-2- ylamino)-cyclohexylmethyl]-methanesulfonamide (15, Lu AA33810) is reported. Compound 15 was identified as a selective and high affinity NPY5 antagonist with good oral bioavailability in mice (42%) and rats (92%). Dose dependent inhibition of feeding was ...