A compound of formula I 1
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-chlorophe-
nyl)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.
