Certain guanidine compounds, and their use as inhibitors of histamine activity

A compound of the formula:

• ##STR6## wherein R.sub.1 is hydrogen or lower alkyl;
• Het is thiazol-2-yl, isothiazol-3-yl or 5-amino-1,3,4-thiadiazol-2-yl, Z is sulphur, oxygen, NH or a methylene group;
• n is 2 or 3;
• X is COR.sub.3, CSR.sub.3, SO.sub.2 R.sub.4 or when Z is methylene, nitro;
• R.sub.3 is lower alkyl, lower alkoxy, or amino;
• R.sub.4 is lower alkyl, trifluoromethyl, amino or phenyl optionally substituted by halogen, lower alkyl or amino;
• or a pharmaceutically acceptable acid addition salt thereof.