| abstract |
ABSTRACT HETEROCYCLIC DERIVATIVES The invention concerns pharmaceutically useful compounds of the formula I, in which R1, R2, R3, R4 and A1 have the various meanings defined herein, and their non-toxic salts, and pharmaceutical compositions containing them. The novel compounds are of value in treating conditions such as hypertension and congestive heart failure. The invention further concerns processes for the manufacture of the novel compounds and the use of the compounds in medical treatment. |