GUANIDINE DERIVATIVES AND PHARMACEUTICAL COMPOSITIONS

This invention relates to alcohol derivatives which are histamine H-2 antagonists and which inhibit gastric acid secretion. According to the invention there is provided a guanidine derivative of the formula I:-in which R1 and R2, same or different, are hydrogen or 1-10C alkyl, 3-8C cycloalkyl or 4-14C cycloalkylalkyl, each alkyl, cycloalkyl or cycloalkylalkyl optionally carrying one or more F, Cl or Br atoms, provided that one of R1 and R2 is halogen-substituted, or R2 is hydrogen and R1 is RS-E-W- in which W is 2-6C alkylene optionally substituted by 1 or 2 1-4C alkyl, E is 0, S, SO, S02 or NR6 in which R6 is H or 1-6C alkyl, R5 is H or 1-6C alkyl optionally substituted by 1 or 2 1-4C alkyls, or R5 and R6 are joined to form a pyrrolidine, piperidine, morpholine, piperazine or N-methylpiperazine ring, or R2 is hydrogen and R1 is hydrogen or 1-10C alkyl, 3-8C cycloalkyl, 4-14C cycloalkylalkyl, 3-6C alkenyl, 3-6C alkynyl, 1-6C alkanoyl, 6-10C aryl, 7-11C aralkyl or 7-11C aroyl, the aryl, arylalkyl and aroyl radicals being optionally substituted; ring X is a heterocyclic ring as defined in the specification; A is phenylene or 5-7C cycloalkylene or a 1-8C alkylene into which is optionally inserted one or two groups; D is oxygen or sulphur; R3, R4 and R5 are hydrogen or a variety of radicals described in the specification: and the pharmaceutically-acceptable acid-addition salts thereof. Manufacturing processes and pharmaceutical compositions are also described.