Substituted 3,4-diamino-1,2,5-thiadiazoles having histamine H2 -receptor antagonist activity

Claim 1

A compound of the formula ##STR35## wherein R 1 is hydrogen, (lower)alkyl, 2-fluoroethyl, 2,2,2-trifluoroethyl, allyl, propargyl, ##STR36## in which q is 1 or 2, R 2 and R 3 each are independently hydrogen, (lower)alkyl, (lower)alkoxy or halogen, and, when R 2 is hydrogen, R 3 also may be trifluoromethyl, or R 2 or R 3 , taken together, may be methlenedioxy, and R 4 is hydrogen, (lower)alkyl or (lower)alkoxy: m is an integer of from 0 to 2 inclusive; n is an integer of from 2 to 5 inclusive; Z is oxygen, sulfur or methylene; and A is a imidazole, thiazole, thiadiazole, oxazole, oxadiazole or pyrimidine; provided that A may contain one or two substituents, the first substituent being selected from ##STR37## or --CH 2 NR 6 R 7 and the second substituent selected from (lower)alkyl, halogen or (lower)alkoxy; R 5 is hydrogen, branched or unbranched (lower)alkyl, (lower)cycloalkyl, or (lower)cycloalkyl(lower)alkyl, in which R 5 may optionally contain one or more halogen atoms selected from fluorine, chlorine and bromine, provided that there is no halogen substituent on the carbon atom directly attached to the nitrogen atom; R 6 and R 7 each are independently hydrogen or (lower)alkyl, or, R 6 and R 7 , taken together with the nitrogen to which they are attached, may be pyrrolidino, methylpyrrolidino, piperidino, methylpiperidino, homopiperidino or heptamethyleneimino, and a nontoxic pharmaceutically acceptable salt thereof.