of formula i other acids are likewise suitable and may be employed if desired for example fumaric benzoic ascorbic succinic salicylic bismethylenesalicylic propionic gluconic malic malonic mandelic cinnamic citraconic stearic palmitic itaconic glycolic benzenesulphonic and sulphamic acids may also be employed as acid addition salt forming acids in the foregoing formula i and elsewhere herein the term 34 lower alkyl 34 and the lower alkyl radical present in the term 34 lower alkyl 34 refers to alkyl radicals containing up to and including eight 8 carbon atoms and preferably no more than four 4 carbon atoms the radicals may have either straight or branched chain structure typical examples are methyl ethyl propyl isopropyl butyl isobutyl amyl hexyl heptyl octyl or the like the compounds of the invention possess beneficial pharmacological properties and are effective pharmaceutical agents the compounds exhibit a circulation stimulating effect the circulation enhancing activity of the substances according to the invention can be demonstrated by known methods one of these methods is the measurement of cerebrovascular resistance on the rabbit according to h hutten and p vaupel cf die medizinische welt 28 1567 1977 the therapeutic effect is expressed in terms of decrease in vascular resistance for this purpose 0 1 ml of a 1 solution of the test substance i e according to the invention.