Heterocyclic derivatives

Abstract

This invention relates to heterocyclic 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: ##STR1## in which R.sup.1 and R.sup.2, same or different, are hydrogen or 1-10C alkyl, 3-8C cycloalkyl, 4-14C cycloalkylalkyl, each alkyl, cycloalkyl or cycloalkylalkyl optionally carrying one or more F, Cl or Br atoms, provided that one of R.sup.1 and R.sup.2 is halogen-substituted, or R.sup.2 is hydrogen and R.sup.1 is R.sup.5 -E-W- in which W is 2-6 alkylene optionally substituted by 1 or 2 1-4C alkyls, E is O,S,SO,SO.sub.2 or NR.sup.6 in which R.sup.6 is H or 1-6C alkyl, R.sup.5 is H or 1-6C alkyl optionally substituted by 1 or 2 1-4C alkyls, or R.sup.5 and R.sup.6 are joined to form a pyrrolidine, piperidine, morpholine, piperazine or N-methylpiperazine ring; 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; and R.sup.3 and R.sup.4 are a variety of radicals described in the specification: and the pharmaceutically-acceptable acid-addition salts thereof. Manufacturing processes and pharmaceutical compositions are also described.