Download PDF Opens in a new window. Article suggestions will be shown in a dialog on return to ScienceDirect. ... Please enable JavaScript to use all the features on this page. ... The development of benzothiazine-1,1-dioxide derivatives as a new structural class of potent endothelin receptor antagonists is described. Structure–activity relationships (SAR) revealed that PD164800 (1) is a potent antagonist of the ET A receptor subtype. ... In our continuing efforts to design ...