A compound of formula I
##STR1##
or a pharmaceutically acceptable salt thereof in which R.sub.1 and R.sub.2
are independently H or methyl (for example
N,N-dimethyl-1-[1-(4-chlorophenyl) cyclobutyl]-3-methylbutyl amine
hydrochloride optionally in the form of its monohydrate) is used for
treating fibromyalgia or neuropathic pain, such as pain associated with
diabetes mellitus, shingles, nerve injury and varied peripheral
neuropathies.
