Abstract: Compounds of the general formula 1; ##STR1## in which R.sup.1 and R.sup.5 which may be the same or different represent an alkyl, alkenyl or alkynyl group, which groups may optionally be substituted by an amino, alkylamino or dialkylamino groups, or by hydroxy, alkoxy (C.sub.1-4), aroyl, aryl or aryloxy groups, in which the aroyl, aryl or aryloxy groups may contain an alkoxy (C.sub.1-4) substituent; and R.sup.5 may in addition represent a cycloalkyl group containing from 4 to 8 carbon atoms or a heterocyclic group;R.sup.2 and R.sup.3 which may be the same or different represent a hydrogen atom or an alkyl group;R.sup.4 represents a hydrogen atom or an alkyl group which alkyl group may be substituted by an aryl or aryloxy group which aryl group or aryloxy group may be substituted by an alkoxy (C.sub.1-4) substituent, or R.sup.4 may represent an aryl group which may be substituted by an alkoxy (C.sub.1-4) substituent; and X represents a pharmaceutically acceptable anion of an inorganic or organic acid.