IPI-616

Replacement of the 4-Me group in a series of N-(3,4-dimethylisoxazolyl)benzenesulfonamide endothelin antagonists with a bromine or chlorine atom resulted in a three- to ten-fold increase in the binding affinity for both the ET_A and ET_B receptors.This potentiation in activities was also observed for naphthalene and biphenylsulfonamide endothelin antagonists.