Method of treating amyotrophic lateral sclerosis with dipeptide derivatives and pharmaceutical compositions for use therein

A method of treating patients suffering from amyotrophic lateral sclerosis to obtain improvement in the clinical symptoms thereof comprising administering an effective amyotropic lateral sclerosis symptom counteracting amount of a dipeptide derivative corresponding to the formula ##STR6## wherein R.sub.1 represents a hydrogen atom, an alkyl group containing one to six carbon atoms, a cyclohexyl group or a benzyl group,

• Z is one of the following groups (attached to the CO-group in the ring by the valence marked with an asterisk) ##STR7## wherein if Z represents a group (a), R.sub.2 and R.sub.3 together represent an additional bond between the carbon atoms to which R.sub.2 and R.sub.3 are attached, or if Z represents a group (b), R.sub.2 is a hydrogen atom,
• R.sub.4 and R.sub.5 may be the same or different and each represent hydrogen or an alkyl group containing one to three carbon atoms, or R.sub.5 also may represent a phenyl group, and
• R.sub.6 represents a hydrogen or a methyl group, in anhydrous or hydrated form, or a pharmaceutically acceptable salt of such a compound with an acid.