Therapeutic agents

Abstract

The invention provides compounds of formula I ##STR1## and pharmaceutically acceptable salts thereof; wherein R.sub.50 is hydrogen or C.sub.1-4 alkyl, A.sub.51 is oxygen, sulphur or a group of the formula --NR.sub.52 -- wherein R.sub.52 is hydrogen or C.sub.1-4 alkyl; A.sub.50 comprises i) a mono or bicyclic aromatic ring optionally containing one or more nitrogen, oxygen or sulphur atoms, ii) a cycloalkendiyl group, or iii) an acyclic bridging group having a chain of one, two or three atoms between the cyclobutenedione group and X.sub.50, said chain being a chain of one or two carbon atoms or a chain of one carbon atom and one or more nitrogen, oxygen or sulphur atoms or iv) a bond; X.sub.50 is either a bond or a spacer group providing a chain between A.sub.50 and B.sub.50 of one or two atoms length; B.sub.50 is a mono or bicyclic aromatic-ring optionally containing one or more nitrogen, oxygen or sulphur atoms; r is an integer from 1 to 6; and Het is a ring system optionally containing one or more nitrogen, oxygen or sulphur atoms or is a phosphonate, phosphinate or amine derivative (wherein each of A.sub.50, X.sub.50, B.sub.50 and Her are optionally substituted). The compounds have angiotensin II antagonist activity and are useful in the treatment of cardiovascular disorders such as hypertension.

Dependencies are inferred from the claim text.